Revealing mistakes: During the Carlos blackboard scene, you can clearly see that the glove knives have plastic or rubber tips on them.
Revealing mistakes: When Freddy appears to Tracey as her father and he turns his glove into a buzz saw, the wires for the fake Freddy arm are visible. Also you can see Robert Englund's right arm sticking down, in front.
Continuity: When Freddy is dropping the needles from above, we see Carlos reaching up with two arms, but in the close-up, he's bending down covering his ears. T
Revealing mistakes: When young Freddy is getting ready to smash the gerbil, we see him sneak it off the table as he puts it down.
Continuity: When Maggie/Katherine wakes up from her last dream, the 3-D glasses can be seen lying on her stomach for a second before she moves.
Continuity: When Freddy is playing the video game he alternates between having one foot up on the edge of the table and both legs crossed in the middle of the table between shots.
Crew or equipment visible: The harness that picks Spencer up is visible on his chest in the close-up of him bouncing across the living room.
Miscellaneous: John falls hundreds of feet and lands on the bed of spikes. When he's in the real world, the suit that shows the spikes is visible.
Continuity: During Carlos's nightmare sequence, Freddy cuts off Carlos's ear. The ear reappears and disappears in subsequent shots.
Crew or equipment visible: When Spencer is almost falling off the edge of the top stair (and the ledge in Freddy's video game), in his shadow you can clearly see the cord attached to his harness keeping him up.
Revealing mistakes: During the Carlos Blackboard scene, you can clearly see that the glove knives have plastic or rubber tips on them.