Corrected entry: Early in the film, when Frank is at the bar (The Blue Note), he orders a Black Russian, however (less than 30 seconds later) the waiter brings him a drink that is definitely not a Black Russian. (00:18:30 - 00:19:05)
Corrected entry: In the bathroom, Savage screws a suppressor onto a revolver. Most revolvers cannot be suppressed in this way.
Correction: While this is true, you have to consider the humor of this movie. So this can't really qualify as a mistake.
Corrected entry: Right after the zoo accident and before the dancing scene, a giraffe runs past a house and it makes a sound, but giraffes don't make any vocal sounds.
Correction: It's a misconception that giraffes make no sounds. http://www.puppetopia.com/giraffe/Info.htm#e.
Corrected entry: Just before Frank bursts through the door that hits Barbara Bush, you can see the special doorstop mounted on the floor to protect the actress from being bopped in the nose.
Correction: Many doors have such rubber doorstops to prevent them hitting the wall or breaking their own hinges by opening too wide, particularly heavily used doors like one in a public room like this.
Correction: The whole scene was a series of gags. The waiter was able to produce the strong man in seconds. The fact he got a random fruity drink so quickly was just another gag.
Bishop73