Corrected entry: In the scene where De Niro is carrying "C" off as a boy after he gives back the money to Sonny, the narration by "C" says that, "His father & Sonny NEVER spoke to each other again". Yet, later in the film when "C" is older, and has just been slapped around by Sonny, when he suspects he had something to do with a bomb being planted in his car, De Niro runs over to Sonny and they speak to each other.
Corrected entry: Right before Sonny shoots the guy in front of C, the guy hits Joe Pesci's windshield with a bat. The windshield doesn't shatter or break open or anything, it just cracks, but you see Joe Pesci come out of the car holding his head in pain as if he was hit with the bat. He would have had to have his head pressing against the windshield in order to be affected at all by the impact from the bat, which he didn't.
Corrected entry: When C goes to meet Jane on their first date, she approaches him and asks him if he was involved in the beating of her brother earlier. After C denies it, Jane yells "Wayne" toward the car for him to come out, then a few seconds later she asks her brother "Are you sure it was him. Willy?", and later in the movie her brother is referred to as 'Willy' as well.
Corrected entry: In the scene where C sees Sonny shoot the man at the beginning of the film, C says, "When Sonny looked at me for the first time I went deaf all I could see was Sonny with a gun in his hand." That can't be possible as we see and hear Sonny's man tell him, "Sonny, give me the gun." and Sonny hands him the gun. When Sonny is walking off you don't see a gun in his hand. (00:15:10)