Visible crew/equipment: When Albert Brooks is driving back to the Aquarium of the Pacific a microphone on his black shirt is visible.
Factual error: The events of the film take place in the early decades of the 18th century. However, in shots outside the front door of the house throughout the entire film there is a large rhododendron bush, a species which didn't arrive in England until the mid 19th century.
Continuity mistake: When Ben Jordan and Stan are walking around the fountain, they walk past a long glass railing. The white sneakers of the cameraman can be seen in the reflection on the glass. You know it's him because he stops walking when they stop and continues walking when they do.
Visible crew/equipment: In the scene where Sean Penn is playing with the big band fronted by the female singer, there is a microphone on a boom visible top center of the frame, when the camera does a pullback to show the whole band at the song's end. (VHS version.)
Deliberate mistake: In the scene where Alicia Silverstone and Dave Foley are in the porno store, they cut to a guy standing behind a counter. All of the explicit shots of the videotape covers on the countertop are blurred out.
Continuity mistake: When Miss Hannigan, Rooster and Lily are singing "Easy Street" outside in the street, Miss Hannigan beats her fur shawl on the ground, and a large piece of fur falls off it. In the next shot, this piece isn't lying on the ground anymore. (00:50:55)
Continuity mistake: Jennifer manages to thwart the nefarious plan of the kids who want to cuff her in the subway. During the scene, Heidi Lenhart's left hand grips the bar in close-ups, does not in other shots. (00:27:20)
Continuity mistake: At the end of the opening credits, Crawford finishes doing the hair of a client and puts his hands on her shoulders. She says "Crawford, you're a genius"; in the wider angle, no hands on her shoulder, and they are back in the following closer view.
Visible crew/equipment: Mini boom mike type thing appears in shot just as the real killer clown is walking onto the stage about to kill Kate. It is visible when he turns to face the 'audience' in the lower right hand corner.
Factual error: The way that Charlie makes the skeleton move is way too complex to be controlled merely by a basic remote controller (which looks like it was originally for an RC car of some sort), which can only control up, down, left and right.