When Joey and Kenny are in Kenny's car arguing after finding the money, just before Joey exits the car, he holds up his bare right hand. Seconds later, Joey is getting out of the car with the sacks in his arms and he's wearing gloves.
When Joey throws nickles at Dino, one of the coins stick to his forehead. Moments later, the coin is gone, then it reappears.
When Vincente Goldoni (Maury Chaykin) holds up a $100 bill and is talking to Joey Coyle (John Cusak), he says Ben Franklin is smiling because he is the only one not to be President. This is incorrect. Alexander Hamilton, on the $10 bill, was never President either.
The movie takes place in 1981. When the Philadelphia Flyers are shown playing a hockey game on TV, player Rod Brind Amour is seen. He didn't join the Flyers until 1991.
Joey says the bags of money are marked for the "Trump Taj Mahal Casino" (in Atlantic City, New Jersey). The movie is set in 1981, but the Trump Taj Mahal Casino did not open until 1990.
When Joey and his mother are talking in her bedroom about Joey's father, she is holding an issue of People Magazine that is announcing the passing of actress Audrey Hepburn in 1993. The movie takes place in 1981, 12 years earlier.
A neon sign in Lindey's bar reads "DON'T WORRY BE HAPPY". That titled song by Bobby McFerrin wasn't released until 1988, seven years after the events of this film.
When Joey finds Katie in his closet, two crew members can be seen in the reflection on the TV. One is wearing a red shirt and is holding a boom mike, and the other is wearing purple and is operating the camera. Also, two studio lights are clearly visible.
When Joey is at the bar and the news reporter is describing Joey's physical appearance, she says that Joey has a tattoo on his right bicep. However, Joey turns and looks at his left bicep.