Cast the Expert: Inverted. The home movie footage was directed by a random crew member because attempts made to shoot it by Scorsese or cinematographer Michael Chapman ended up looking too professional.
Creator Breakdown: Scorcese was struggling with a cocaine addiction at the time and planning on retiring as a director. De Niro specifically brought the project to Scorcese in hopes that its themes of self-destruction would help Scorcese overcome his problems.
Dawson Casting: Cathy Moriarty playing a fifteen year old version of her character at the begining (she was 20).
Somewhat justified, as she portrays the character from her teens until her late 20's.
There's also the fact that Robert De Niro was 36 or 37 at the time of filming, and in the early scenes played a 19-year-old Jake LaMotta.
Dyeing for Your Art: Robert De Niro put on 60 pounds to play the retired Jake LaMotta, arguably starting the trend.
Enforced Method Acting: Joe Pesci never knew the script called for him to be attacked, so the scene where De Niro beats him up at dinner came completely out of nowhere.
Playing Against Type: Joey LaMotta is played by Joe Pesci. Yes, that Joe Pesci. Of course, it was before he was typecast. Pesci still manages to start a fight by breaking a glass over someone's head, and ending it by slamming their head and shoulders repeatedly in a car door. He does apologize after, but only at the insistence of an old mobster.
It still counts, though, as compared to DeNiro, he's really the collected one. It's Jake that has the Hair-Trigger Temper.