Nick's People's Choice Award breaks in two when he throws it at the TV. When Angie picks it up, it's intact.
When Moss gives an interview in front of one of the latest victims of the Party Crasher he is heard saying to the interviewer, "he may not even be a man, I doubt he's got the equipment for it." Yet when the same interview appears in the Party Crasher's apartment, Moss says "I doubt he's got the right equipment for it."
The green face mask worn by the Party Crasher changes several times, from smooth to crumbly.
When Moss chases Party Crasher into the movie theater, his fingers are bandaged as he talks into the walkie talkie. When he got out of the car to chase him, his fingers weren't bandaged. Later when he talks to Lang, the bandage is gone.
Nick and John cover their "Frog Dogs" with ketchup and mustard but when they pick up the hot dogs there is not much on them.
One item in the film creating tension between John Moss and Nick Lang is that Captain Brix has ordered Moss to let Lang stay with him in his apartment. In reality neither Brix nor any other supervisor could lawfully order Moss to let Lang stay at his apartment, as the apartment is Moss's home, and he has the right to determine who he lets stay at his apartment.
Early in the movie a car is released from a tow truck and it flips. The piston and the metal frame used to flip it are clearly visible during the flip and the subsequent roll of the car.
Roll bars are visible as the police car overturns near the end of the movie.
When the Party Crasher loses the gun and it lands perfectly on the rim of the giant hat, fishing wire is visible attached to the handle. Likely, gun was yanked away from the edge and the shot reversed. Later, when the Party Crasher picks the gun up again, the wire is gone.
When John falls over the edge of the giant billboard hat, the face of the stuntman is clearly visible.
When Nick is hanging off the "Smoking Gunn II" billboard by a rope, in one shot you can clearly see that he is actually wearing a rappelling harness.
When Nick is pretending to be John's girlfriend in the bar, he sighs. Even though his mouth his wide open as he sighs, he says, "Susan".
When Susan is hanging off the large hat of "Smoking Gunn II"'s billboard, she says, "John!" but her mouth says, "Hey!"
When Nick Lang first meets the captain in his office, the captain asks for a autograph. You hear Nick say "Absolutely" but his mouth does not move.
When John Moss is being carried away by the Party Crasher towards the cigarette prop in Nick Lang's sign, he is heard yelling "Oh s***" as he is about to crash onto such prop, but his mouth is seen simply open.
When Susan is knocked onto the large cigarette on the "Smoking Gunn II" billboard, the safety wire is visible.
The opening chase scene from the nightclub starts on West 46th Street in midtown Manhattan, then quickly shows cars turning off of Pearl Street in lower Manhattan.
The subway shootout was shot in the Hoyt-Schermerhorn subway station in Brooklyn ("HOYT" is visible on the walls), even though all exterior shots show the station as Brooklyn Bridge-City Hall in lower Manhattan.
Nick Lang's police car doesn't have a partition between the front and back seats.
The Party Crasher is seen multiple times by police officers and large crowds with seemingly dozens (if not hundreds) of witnesses, and apparently seems to be wealthy as he lives in an expensive, well-decorated loft in New York City. Because of this, his identity should have been easy to discern, leading to his quick arrest.