Factual error: The paramedics apply the neck collar to Kick Ass after he was hit by the car. The problem is he is already on the spinal board when it is applied. Neck collars are always applied before putting the patient on the spinal board, especially when head or neck injuries are suspected as would be the case in being struck by a car. Even if there were no witnesses to him being hit, paramedics would assume a neck/head injury if no one saw the incident. Also, the paramedic doesn't immobilize his head before applying the collar, and is far too rough in putting it on.
Continuity mistake: During the scene at Razul's, the placement of the boxing gloves above the punching bag changes several times throughout the scene.
Dave Lizewski: How do I get a hold of you?
Hit Girl: You just contact the mayor's office, he has a special signal he shines in the sky. It's in the shape of a giant cock.
More trivia for Kick-Ass
Question: What's the name of the song that plays when we see Hit-Girl beat up Rasul's (or however you spell that) thugs?
Answer: It's a modified version of the "Tra La La Song" from the Banana Splits TV series of the 1960s. http://en.wikipedia.org/wiki/The_Tra_La_La_Song_(One_Banana,_Two_Banana).
Jeff Swanson