Continuity mistake: When Bronx go to sleep intoxicated (the night the medicine man paints on her face) she is wearing a shirt and panties, but when she wakes up she is wearing a pair of jeans.
Factual error: The old man is supposed to have accidentally ended up at Rita and Peter's wedding by just "getting on a train," and finding himself in Lake Forest (a far northern suburb of Chicago.) But he started out in Berwyn (a western suburb), and in order to get to Lake Forest from Berwyn, you have to get on one train, get off in downtown Chicago, walk several blocks, and then get on an entirely different line going to Lake Forest. In other words, not something you can "accidentally" find yourself doing, but something you have to know where you are going in order to do.
Visible crew/equipment: After Jack jumps out of the plane he comes close to another Flying Elvis, who is being suspended from a visible cable.
Continuity mistake: At the beginning of the film, Mary and Roger's nanny Brenda refers to Mary as "Mrs. Anderson", but according to the credits, Mary and Roger's last name is Charleston.
Continuity mistake: As Lloyd leaves the stage asking what the show will be without him, Poppy's standing in the middle of the stage. But in the next shot she is leaning against the proscenium.
Factual error: Some characters are shown at Paddington Station and in the background the train shown at the platform is a 1920s Southern Railway green electric driving coach. Paddington at the time of the film was home to the Great Western Railway which never operated electric trains and never used green livery on carriages. Furthermore the carriage was issuing copious amounts of steam (accurate for the period and venue) but impossible from an electric train.
Continuity mistake: When Gwen is in the house discussing "what happened in Maui" with Becky (Davis is there also), her sweater sleeves are pushed up by her elbows. After she finishes the story she leaves the house. In the next shot, Davis thanks Gwen for making up the story (they are outside of the house). Her sweater sleeves are now down around her wrists.
Other mistake: Jack's slap across Nick's face didn't make contact. (01:25:40)
Other mistake: When the police drop their weapons to chase after the screaming woman who just took the concentrated love potion, you can see the machine guns have no magazine clips in them.