Continuity mistake: In the scene where Harry and Marv are at the skating rink, the front of Marv's hair is constantly changing from shot to shot. It's either poofy or pulled back due to the earmuffs he's wearing.
Revealing mistake: When Mandy falls inside the Porsche, her stunt double is noticeable because she is way older than her.
Continuity mistake: When Madeline is given the card with address of Lisle Von Rhoman on it, she tears it down the middle into two, and the two pieces she tears are torn neatly and straight down the middle. Yet later, when Madeline takes the two pieces of the card from her bag, they are torn much differently, and aren't torn straight and neatly. (00:19:45 - 00:28:20)
Continuity mistake: At the beginning, there is a scene where Ben spills a carton of milk. He picks it up right away, but a split second later the scene changes, the milk is still lying down, and he puts it upright again. (00:06:25)
Revealing mistake: In the chase scene about an hour into the movie, Robert Loggia is shown entering the Liberty Tunnel, driving on a wet road. Note the vaulted round ceiling of the tunnel. Next, we see a series of shots of him in the tunnel, and then a shot of the sun rising over Pittsburgh as he is about to leave the tunnel. Here is the problem - the sunrise shot is taken from the Fort Pitt tunnel on a different day. Note the dry road, the barriers to the driver's left at the tunnel exit and the Fort Pitt bridge straight ahead. There is no place for the driver to make a left turn out of this tunnel. Also note that the POV is from the left lane. All the Liberty Tunnel shots show Loggia in the right lane. The next shot shows Loggia exiting the Liberty Tunnel and making a left turn from the right lane, causing a pile-up. (01:11:10 - 01:12:20)
Continuity mistake: After Fifi sings her line of the opening song, a stack of textbooks on Bugs Bunny's desktop changes appearance between shots. (00:01:45)
Visible crew/equipment: When Charlie is in the ventilation system and says, "I could use some help here," the boom mike briefly pops into the picture. (00:44:40)
Continuity mistake: When Robert Redford tips the scrabble letters onto the glass table, he makes "SETE" and "CAST" next to it. To the right of "CAST", under his right hand, are the letters RNY, quite widely spaced. All other letters are tightly gathered above. When the angle changes to under the table, suddenly all the letters are spread fairly evenly around the table. (00:39:15)
Continuity mistake: Near the end of the movie in the scene where Garth is stabbing a doughnut-person with a hockey stick shaped pencil, the eraser changes from pink, when he's stabbing it, to blue, when it's standing on its own.
Visible crew/equipment: When Eddie arrives at the casino near the end of the film, he opens the car door and in the reflection you can see the filming crew.
Visible crew/equipment: During the final song, while they're all at the dinner table, there's a crouching puppeteer with a blonde ponytail next to the rats.