Deliberate mistake: As "Fake Dolly" runs away from Gracie, it is rather obvious in the shot facing Dolly as she runs down the stairs and then when she turns to look behind her, that it really is a fake Dolly running. (00:48:20)
Deliberate mistake: When Foreman is taking Gracie, and Sam to the hotel, you can look behind Foreman at the background you can see the newer Las Vegas Strip. At first, you can see them going toward the bridge that connects the MGM Grand to New York, New York. In the next shot, you see a completely different part of the strip that is nowhere near New York, New York. Then when Sam says "Where's the best place for me to throw up?" if you look behind Foreman, you can see the Brooklyn Bridge, which means that they are now going the other way.
