Continuity: In the beginning of the Roman Empire Segment, one of the running jokes was the use of a V in place of a U. It seems that great care was taken to do this on every sign. Except the Annual Orgy sign which has two Us on it that were not changed to Vs.
Anachronisms: When Comicus, Josephus, Swiftus and Miriam are being chased by the Marcus Vindictus, modern tire tracks are clearly visible on the road.
Revealing mistakes: When Josephus slips on the banana peel, his foot misses the peel.
Continuity: As Comicus and Swiftus are watching Josephus performing on the slave auction block, there's a girl standing behind them in some shots and not in other shots.
Continuity: In Caesar's palace during the feast, wine is spilled on Caesar's toga but the stain disappears in subsequent shots.
Factual errors: In the Roman Era, the sign for the orgy states that it is held in the Temple of Eros. Eros is the Greek God of Love not the Roman. It should be the Temple of Cupid.
Revealing mistakes: In the Spanish Inquisition musical number, the nuns do an underwater show that ends with them standing on a menorah. It is clearly visible in the movie that the action is in reverse.
Audio/visual unsynchronized: When Comicus is pulled into the Virgin room by Miriam, one of the virgins' says "Who's that?", but her mouth does not match "that".
Revealing mistakes: When Comicus, Miriam, Swiftus and Josephus reach the 'river', the tops of the water remover are obviously visible just below the surface. Later, it is obvious that the water is being dumped into a pool-like area in the middle of the river to create their path.