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.
There is a scene in which Joey throws nickles at Dino. One of the coins stick to his forehead. When the scene comes back shortly, the coin is gone, but when the scene focuses on Dino again the coin is back.
Joey Coyle found the 1.2 million dollars in 1981. There is a scene where the Philadelphia Flyers are on TV and you can see player Rod Brind Amour who didn't join the Flyers until 1991. The year Joey found the money Rod Brind Amour was only eleven years old.
When Maury Chaykin(his character Vincente Goldoni) holds up a $100 bill and is talking to John Cusak(his character Joey Coyle), 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.
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, 12 years after this movie was supposed to have taken place.
The movie is set in 1981. Joey says the bags of money are marked for "Trump Taj Mahal Casino" (in Atlantic City, NJ). The Trump Taj Mahal Casino did not open until 1990.
When Joey finds Katie in his closet, 2 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, 2 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.