Continuity mistake: When the young Sullivan boy goes to get Rooney's over coat, he walks into the room where the coat is and there is a man laying on the couch, if you notice when the man starts talking to the boy, his cigarette is almost gone, and in the next few seconds it flashes to the man again and he has a cigarette that is almost full. (00:09:20)
Continuity mistake: In the scene where Tom Hanks is battling Jude Law in the hotel room, just before you see Hanks shoot the glass vase that shatters in Law's face, there is a shot of Tom Hanks jumping out behind the chest to get the final round off. Unfortunately, Tom Hanks's 1911 is empty in that shot - you can see the slide locked back.
Continuity mistake: In the scene where Paul Newman's character hands Michael, Jr. a silver dollar, the first camera angle (from Michael's perspective) shows the "heads" side presented toward the kid. The next angle (from the opposite point of view) also shows the dollar with the "heads" side toward the camera, which means the "tails" side (an eagle) is what the kid should have seen.
Continuity mistake: Look carefully at the Lone Ranger book that Michael Jr. is reading at two points in the movie (once when he's reading in his bed as he and his brother are talking about their dad, and again in the car after his mother and brother are killed.) The picture and caption under it are identical, but the text on the facing page is different each time.
Continuity mistake: When Michael is sent to go get Rooney's suitcoat, he isn't allowed to get it, and when he appears downstairs just after coming from the study, Rooney is speaking, with his suitcoat on. Rooney didn't have time to get it.
Continuity mistake: In the scene where Michael Jr. is riding home on his bicycle (before his mother and brother get shot) he drops his bike and runs to the house. A few minutes later when Tom Hanks is driving off with Michael Jr., it shows his bike. The bike has snow covered on it, but it is not snowing, the snow has stopped.
Continuity mistake: After the night scene of heavy rains, you would expect at least some of the snow to melt the next morning. But if you look closely, the snow mounds in front of the Sullivan home are identical to the shots in the first few scenes, before the heavy rain.
Continuity mistake: When Hanks dies at the end, you can see his left hand laying on its side, but in a wide angle shot of the same scene, you see his hand laying on its back.
Continuity mistake: When the mother and son are shot, it shows from the outside, and the gunfire flashes in the one (suspected) bathroom where they were killed. Just before, the light was on, and then when Jr. went to find them, the light was back on.
Continuity mistake: During Sullivan and Maguire's gun fight at the hotel, between the fifth and sixth shot Maguire takes at Sullivan, a bullet imprint instantly appears on the trunk Sullivan is taking cover behind, in the top right corner.