Visible crew/equipment: When Comicus and his entourage are on the road to Judea, the tire tracks of the vehicle carrying the camera are blatantly clear in the lower part of the picture.
Revealing mistake: During the Inquisition song when Right Before Mel Brooks Plays bongos on the guys heads he slides in from behind the wooden torture things. If you look closely the hair on the stunt double sliding in is darker than Mel's.
Revealing mistake: When Comicus et al are running from the Roman soldiers, Miriam pulls Comicus through a secret marble door. When it closes, you can see the glue residue revealing that it's Formica.
Audio problem: When Comicus is announced in Caesar's court, the trumpeters play "Hooray for Hollywood". Notice that the music starts before they get their instruments to their mouths.
Continuity mistake: In the scene where Caesar orders his guards to kill and seize Mel Brooks, he calls for more wine and a servant comes to pour him some If you notice his shirt, it is clean and white. In the shot right after he calls for it, when the servant is walking up behind Caesar laughing, you can see that Caesar's shirt is stained purple. This is caused from repeated takes, because right after the servant walks up he spills the entire container on Caesar. But yet, in the finished movie, Caesar's shirt is purple before it even gets spilled on.
Other mistake: After Leonardo sets up his canvas to begin painting The Last Supper with Jesus with his disciples, he says "hold it" and then the camera flips to show the men (and Comicus) now situated behind the table. Look at the disciple in the blue tunic at the right, who first looks off to his right, then corrects his position, and faces left, with his arms extended. (00:52:32)
