When Frank comes down from the train platform at the end of the movie, he's carrying a briefcase/bag of some type. When he's chasing Michael down the streets, he's no longer carrying the bag.
When Michael is dancing in the nightclub, wearing a trench-coat, he spins around in a circle and his trench-coat floats up a little, and there are no wings available, but then immediately following the spin, his wing tips are sticking out from the bottom of the trench-coat.
When Michael is in the field after Sparky has been run down by a truck and he is facing Dorothy, Frank and Huey, the sun is on right hand side and is bright. When the shot goes back to the other characters, they are facing Michael and the sun is also on their right hand side and is obviously lower in the sky.
After the bullfight, the reporter is shown with his tie over his left shoulder, when shot form the front. From behind, the tie is not over his shoulder.
In the opening scene of the movie, there is a flag seen outside of the First Commerce Bank. When the shot is further away, there is no longer a flag.
While Pansy Millbank repeatedly says she is making eggs "over easy," she clearly makes scrambled eggs.
During the first breakfast scene with Michael, both Dorothy and Frank order their eggs over easy, but you can clearly see that they both get scrambled eggs.
When the group first leaves Pansy's house, and they're driving down the highway on their way back to Chicago, the rear-view mirror appears and disappears, depending on the shot. Views from inside the car show the mirror. Views looking in from the outside reveal the mirror is missing.
At Joe's, the first restaurant the group stops at, the waitress brings the food and, within minutes, when Micheal gets up to dance, the waitress comes back and takes Dorothy's plate without her having eaten anything from it. The waitress then sets down a cup of coffee.
When Michael is sitting outside of Brown's Motel, talking to Sparky, big rolls of hay can be seen relatively close to them. In later shots, the hay is in a field much farther off in the distance.
Near the end of the movie, there is a camera shot of a Christmas tree with an angel at the top. However, the angel is holding a horn. That angel is Gabriel, not Michael.
When Michael is in the back of the car, counting down the ten seconds before the tire blows, the audio is saying "seven hippopotamus, six hippopotamus..." but Michael's mouth isn't.
In the scene where Michael is bringing Sparky back to life you can see a glimpse of the wire extended his left wing.
When all of them are driving to downtown Chicago to see the Sears Tower, there's a shot of the car driving down the highway. Then in the next scene you see them driving down another highway with the lake on the left, and the John Hancock Tower in front of them. This is impossible because the first highway is I-90 and the other highway is Lake Shore Drive (U.S. Route 41). There is no direct way to go from I-90 to U.S. 41. Actually, I-90 and U.S. 41 meet in Northern Indiana, but this would be a circuitous route and if 41 was taken from Indiana, Lake Michigan would be on the right, going to the Sear's Tower.
Michael: "Remember what John and Paul said." Frank Quinlan: "The apostles?" Michael: "No, the Beatles. All you need is love." Paul wasn't one of the twelve apostles. While Paul was not one of the original 12 apostles, he was later commissioned by Christ to be an apostle to the Gentiles.