When Michael is writing the letter to Debbie the pen he is writing with is yellow with a blue top but in the next shot when he brings the pen up it is clear with a black top.
On the boat, Toni's purse alternates between being on and off her shoulder, in the final shot she throws it off and jumps in the water.
When Michael has a scuffle with Steve and steals his car we clearly see that the right side of the vehicle is dented when Michael gets into it. Onwards, every following shot will show a perfect car body.
When Michael pulls into the park with Deborah Anne Fimple there are no open spots around him, but in the next shot we see Michael's father pull in into an empty space next to Michael.
At the end when Michael is chasing Toni's car, you can see as the car turns the corner, the window is down on Toni's mom's side. Michael is only about 30 feet behind the car. At this point, it isn't likely that Toni's mom didn't hear him screaming Toni's name or even look in the mirror after hearing him.
During bridge night, when the scuffle between George Ryan and Lou Fimple goes to the ground, there is dialogue between the two, but their mouths do not move.