Continuity: During their fondue dinner, the arrangement of the fondue forks in the pot changes drastically between shots.
Continuity: When Mr. Jinx lets Little Jack out of his playpen, the gate is left open. However, in the next shot when Moses the dog is chasing Mr. Jinx, the gate is shut and properly locked. In the next shot, the gate is open again.
Continuity: When Roz is giving Jack a massage, Greg opens the blinds to look into the room. When he opens the door, the blinds are closed. In the next shot, however, the blinds are open again.
Continuity: The amount of whipped cream on Bernie's face changes between shots, even after he has stopped wiping it off with the towel.
Continuity: During the entire dinner scene, the amounts of wine in the glasses change several times.
Continuity: When Greg walks in on his parents, he is holding the cowboy hat in his right hand, in the next shot, however, he is motioning with the cowboy hat in his left hand.
Continuity: When Roz, Pam, and Dina are shopping, Pam holds up a blue dress and looks at it in the mirror. In the mirror angle, she isn't smiling, but in the next shot she is smiling.
Continuity: After Little Jack, says the curse word to Jack, you can see Pam put her hands to her mouth in the background, but in the next shot, her arms are still down and then she puts her hands to her mouth.
Continuity: When Greg goes into the room where Jack and Dina will be staying, he moves a figurine from the bedside table, hiding it behind the table itself. When they end up going in later, the figure is back where it started.
Continuity: When Greg is looking throught Little Jack's basket of toys, he holds up the wooden plank with the colored blocks on it, but in the next shot, the block colors are reversed even though he didn't turn the plank around.
Revealing mistakes: When Greg picks up the brick to throw at the RV, we can clearly see it "compress" in his hand, showing that it is made of sponge, not real brick.
Audio/visual unsynchronized: When the minister is playing the wooden flute at the wedding, the pipes he blows are clearly unrelated to the sounds being produced (low notes vs high notes). Also, his mouth moves to other notes on the flute while the previous note continues to be heard.
Continuity: The plunger in the syringe of sodium pentothal changes its position between shots.
Continuity: Jack's hand changes position on the brick between shots as he is trying to give it to Greg.
Continuity: When Bernie is lying in front of Jack's RV, his position changes from shot to shot although he does not move
Continuity: When Jack is making the announcement in the RV there is a shot of Greg clapping. In the reflection of the window Jack is speaking into the microphone. Then when finished talking he puts the microphone back into it's place. Jack offers to let Greg honk the horn. When Greg says, "Sure" the reflection of the window shows Jack still speaking into the microphone even though he had set it down.
Continuity: During Jack's massage, his head is alternately on/off the headrest between shots.
Continuity: The amount of lipstick on Greg's face after Isabel kisses his cheek at dinner.
Revealing mistakes: When little jack is discovered to have glued his hands to the rum bottle, a string and possibly some tape are visible holding the bottle to his hand.
Audio/visual unsynchronized: When Bernie is going to fight with Jack, Jack warns him that it would "bring his demise". While Jack is speaking the camera is shooting over his left shoulder and it can be seen that Jack's mouth is not moving.
Audio/visual unsynchronized: When Greg and Jack are talking while driving in the camper at night, the shots of Greg all show Jack reflected in the window beside him, and vice versa. In a few of these reflections, the person appears to be speaking when they are not - and Jack is seen speaking into the microphone when he is not.
Continuity: The cherries in Greg's drink appear and disappear between shots when they are having a drink after the two families first meet.
Revealing mistakes: LJ's body double... a doll with completely different colored hair is seen in at least two shots. One in the trailer, when Jack is explaining the feeding process and the other, when he is supposed to be sleeping in the crib...
Continuity: When Greg and Pam are getting ready for their trip to Florida the zipper on the suitcase changes position from open to closed to open.
Continuity: When Greg is talking to his parents there are two candles to his right by the door. In the first shot both candles are lit, in the second - only the top candle - and in the third they are both lit again.
Continuity: When Bernie is going to fight with Jack, Jack has his arms folded in some shots but not others.
Continuity: When Jack meets Greg's "supposed" son at Isabel's home for the first time, Jack alternates between having his arms crossed with his hands on his hips between shots.
Continuity: When Jack and Little Jack are driving off in the RV, the reflection of the camera crew is visible on the outside of the vehicle. Jockstrap on the Wall of Fame disappears between shots
Continuity: Upon Greg and the Byrne's arriving at the Fockers' home, Greg hugs his father. Bernard is sweating and when he hugs Greg, the sweat disappears and reappears between shots.
Continuity: While they are playing football in the yard, Bernard's sweat changing between shots.
Continuity: When Greg and Jack are talking in the RV while on the way to Greg's parents house, Jack makes an announcement on the PA system. After he puts the microphone down, you can still see it in his hand in the reflection in the window behind Greg.
Errors in geography: In Chicago street signs are green not blue.
Continuity: When Gaylord has been injected with the truth serum and is talking on stage, his microphone is sometimes loose in his hand and sometimes stuck on the microphone stand.
Continuity: When Bernie is sitting on the toilet while Jack is in the shower, in one shot he has bare feet and the next he has socks on.
Continuity: When the whole family is eating supper on the formal dining table, the little Jack is behind the mom and dad of the girl in his playpen. When they change back and forward to Gaylord the kid disappears.
Factual errors: There is no Latvian naming tradition like the one Gunther describes.
Continuity: When Greg is talking to Roz after interrupting her sex therapy class, Roz's hand is on Greg's shoulder in one shot, then is free in the next.
Continuity: When Bernie is first introduced in the film he hugs and kisses Greg leaving some sweat on Greg's shirt. The sweat alternates from a spot of sweat to a long line of sweat and back again between shots.
Continuity: During the engagement party Jack hands his daughter a "wine spritzer" to take to her mother. The color of the drink changes from dark to white between takes
Continuity: In the wedding dance scene, we see a sequence of shots in which Pam can be seen alternately cradling LJ or not holding him at all.
Continuity: While Greg is babysitting Little Jack and sings the song, LJ's hands change positions from shot to shot.
Continuity: When Greg talks to Roz for the first time she hugs him and her hands are on/off/on his shoulders between shots.
Continuity: When Jack takes 3 quick photos of Jorge with his camera pen, Jorge is not smiling and he is looking straight ahead. However, when Jack uploads the photos in the email he sends from the command center of the RV, Jorge is smiling in the first photo and has his head turned in the third photo. Also the speed at which the camera takes the photos would be too quick for any physical movement to be made in between.
Crew or equipment visible: When the RV drives off, in the reflection you can clearly see a tent and crew standing around.
Audio/visual unsynchronized: In the scene with the RV, Ben Stiller's parents come into the RV carrying the dog. Jack is holding the cat and then the animals start chasing each other. After they already show them running, the camera goes to Jack and he's still holding the cat.
Continuity: After Jack gets the massage from Roz, he heads to his camper. After straightening out his back he starts buttoning his shirt as he walks. In the next shot, his shirt is completely buttoned and neatly tucked in his pants. The was no time for him to do all this in the time he was walking.
Continuity: When Greg throws down the TV remote, it is faced down so the black is visible on top. After Greg leaves, the remote has changed sides and is now facing up with the buttons visible.
Continuity: When Dina has the scrapbook during dinner, she is seen holding the book open to the circumcision page and then flipping through the following pages but in the next shot the book is open back to the circumcision page.
Factual errors: Sodium pentathol works as a truth serum in that it relaxes a person and does make them very communicative, sharing thoughts without hesitation. This makes them easily guided in questioning since they speak first and think later. However, the person loses inhibition but not self-control. The person will not simply begin to spill information if they choose not to or are not prompted to do so. Sodium pentathol is also a commonly used anesthetic. A syringe with a highly concentrated dose of that amount would have put Gaylord out cold on the floor. He wouldn't have been awake enough to tell the truth.
Errors made by characters (possibly deliberate errors by the filmmakers): On the next day after the party, when Jack is sitting in the RV about to leave, Gaylord is shouting at him. While mentioning the injection of the truth serum, he points at the wrong side of his neck. The serum had been injected on the opposite side.
Continuity: When Jack puts the little camera in the crocodiles mouth you can see that the camera is tiny but when he cleans the lens the camera screen shows that he is cleaning a bigger lens.
Continuity: After receiving the truth serum, Gaylord is introduced by his Dad to come up to the stage. His wine glass is full in the first shot, but the shots after that the glass is almost empty.
Factual errors: In the scene where Jack is teaching sign language to the baby,the word Truth is written in different languages. However, the Farsi translation of the word is written wrongly compared to modern Farsi.
Continuity: At the wedding, Bernie mentions having been Greg's father for 36 years. But one major plot line revolves around Greg being 19 when he lost his virginity, and that this happened exactly 15 years ago. If Greg was 19 years old 15 years ago, this would make him 34, not 36.
Errors in geography: Jack's home is in Coconut Grove, which he says is an island. It is not; it's a neighborhood located south the Brickell neighborhood of downtown Miami.
Continuity: During the football game, just after Bernie's knocked over Jack, you can clearly see the football on the grass. But then in a following shot, the ball is seen in the air falling to the ground.
Audio/visual unsynchronized: In the scene when Greg wakes up in his parent’s bed, he holds the note left for him by Jack. And although he's holding it perfectly still, you can hear the sound of crackling paper.
Continuity: When everyone discovers the baby with the bottle glued to his hand, Roz hold up the bottle of glue and it is completely clean and closed.
Continuity: At the end of the film Jack says that he has around 20 minutes until the cake is cut. However, shortly after this the cat and dog are shown eating a piece of cake. The cake is then shown to be uncut.
Errors made by characters (possibly deliberate errors by the filmmakers): The girls on the "horny" bus have a banner that exhorts drivers to "Honk if your horny," instead of "you're."
Errors made by characters (possibly deliberate errors by the filmmakers): When Bernie is lying under the RV to prevent Jack from leaving, he says that that was how they did things in the '60s, except he says 'Ben' instead of 'Greg'.
Continuity: When Bernie goes to kick Jack, his foot swings past him to the right to hit Greg, but in the just previous shot Greg is standing the other side of Jack, so Bernie would have hit him first anyway.
Factual errors: In Judaism, the circumcised foreskin is kept and then buried in the ground. It would not have been kept in a scrapbook.
Errors in geography: The trees shown lining the streets of Chicago do not grow in Chicago.
Errors made by characters (possibly deliberate errors by the filmmakers): Ross Focker says that "they're probably down in in Little Havana having chimichangas." Little Havana is a reknowned Cuban area and traditional Cuban food does not include the Mexican dish of chimichangas.