After Bialystock and Bloom enter Roger de Bris' house, Carmen Ghia immediately asks them to take off their shoes to keep the white carpet clean. While on a shot of their faces, both are seen to take off their shoes and audio is heard to that effect. Yet when they get into the small elevator immediately after and in subsequent scenes with Roger de Bris, they are wearing shoes.
In the bar during the intermission, the way 'see/hear/speak no evil' is done changes.
In the bar The Drunk is between Max and Leo as the patrons leave for the second act. After the shots of Max putting his head on the jukebox and Leo caressing his blanket when Max comes back to the bar, to calm Leo down, The Drunk has disappeared.
When Max wipes coffee off his window with his scarf, it becomes dirty. It is clean a moment later.
Max hands Leo a cigar. Leo has the cigar in one shot, and then the next shot of him, it's gone.
This movie makes a common mistake. Dynamite cannot be detonated with a lit fuse. It requires a blasting cap detonation.
Franz Liebkind fires 10 shots from his Luger pistol, but the Luger has only an 8-round magazine.
There is no way an extravaganza like "Springtime For Hitler" could appear on Broadway without an extensive preview season before live audiences as well as many rehearsals involving the huge cast. The pro-Hitler nature of the production would have become common knowledge in New York well before opening night. Yet the audience on opening night is shown to be in a state of shock after the first musical number.
On opening night, the shots of people getting out of their cars show the Cort Theatre on the other side of the street. There is now no theatre across the street from the Cort but until 1969 it was Broadway's Playhouse Theater.
In the restaurant with the violin player, the violin is obviously a prop as the strings are slack and move easily when bowed.
Just before Franz Liebkind shoots the office door open, the fillers covering the explosive squibs in the door are visible.
In LSD's number "Love Power", his musical ensemble consists of a guitarist, keyboardist, and sax player; however, the music heard clearly has flute, bass guitar, drums, and other instruments not represented, but no saxophone.
During the mass Hitler audition, as Roger De Bris jumps up from his seat to go onstage, his dialogue and the movement of his lips don't match.
After Max Bialystock gets into his cab to go to the Blue Gypsy, cables are visible as the cab pulls away from the curb.
The notice that Max and Leo place in Variety simply states that they are auditioning for the role of Adolph Hitler- making no mention of singing or dancing- which most people would not even think of for that role- yet actors arrive with music and/or dressed to dance.
During the time in Liebkind's flat and leaving it Max and Leo are wearing Nazi bandages on the right arm. However the real swastika bandages were worn on the left arm. Since Franz Liebkind was a "true" Nazi, he should have known that.
When Max and Leo are about to enter Franz's apartment building, a pretty woman passes by and they check her out. In the distance, a young man exits another building; as the woman gets closer to him, they obviously don't know one another. When Max and Leo leave Franz and walk onto the same sidewalk in front of the building, the very same pretty woman can be seen walking towards them; what's more, she is with the same young man who was exiting the building, and now they are a "couple."
When Max is reading aloud the opening line of Franz Kafka's "Metamorphosis", the script he's holding is upside-down.
During the Springtime for Hitler dance number, the woman in the kick chorus line at the far left misses both initial and last kicks.