Continuity mistake: When the 3 guys are kicking a single guy with Kick-Ass defending him and a bunch of people behind watching the fight, the trashcan on the ground keeps changing positions between shots.
Continuity mistake: Towards the end of the film after Hit Girl strikes one of D'Amico's henchmen with two kitchen knives you can see the position of the knives in the henchman's chest change position between shots. (01:41:45)
Continuity mistake: During the scene at Razul's, the placement of the boxing gloves above the punching bag changes several times throughout the scene.
Continuity mistake: During the scene at Frank's Lumber Supplies, Red Mist's black makeup disappears, only to reappear later.
Continuity mistake: Joe is eating a cigar shaped piece of bread or something, and at 20:15 he takes a bite and there is very little left in his hand, then at 20:19 it shows him holding the piece and it is much bigger than before. (00:20:15)
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: When Hit Girl is lying down on the crushed table after fighting with Frank, the amount of blood under her nose constantly changes between shots.
Continuity mistake: Kick-ass grabs the hand of the dude in the red jacket and goes in to bash shoulders with him but in the next second he has the hand of the guy in the green jacket and bashes shoulders with him. (00:02:40)
Continuity mistake: In the scene where Red Mist and Kick Ass are in the Mist Mobile in order to go to the warehouse, Red Mist send a text to D'Amico's men. We cut to the warehouse, where one of them is making a joke. He gets the text, reads it for like a second, sends the others away and puts the phone to his ear. Later, when Red Mist plays the video feed to D'Amico, the guy barely looks at his phone before putting it to his ear, then sends his men away.
Continuity mistake: During the scene in the bowling Alley, after Mindy says that she'd like a "Bratz Movie Style Make-Over, Sacha," she places her spoon in her ice cream glass and lets go of it. In the next shot, the spoon is back in her hand, and she is shown placing the spoon into the glass again, without having removed it from before.
Continuity mistake: In the Hit Girl corridor fight scene where she takes out several guys, the table at the end of the hallway she jumps on to take out the last guy is continuously changing positions between shots.
Continuity mistake: When we see the Mist Mobile sometimes the doors open straight up like on a Lamborghini. Other times, they open like normal car doors.
Revealing mistake: Throughout the movie, people getting shot almost always don't have the shot angles line up with how they appear. This is especially obvious in the end scene with Hit Girl shooting the gangsters: she might shoot someone at an angle from the side, but the shot appears to have come from directly behind the person.
Continuity mistake: In the scene where Marcus reads the comic showing the origins of Big Daddy and Hit Girl, we see a closeup of the last but one page, but when Marcus holds the comic book up to Damon in the next shot, the page is completely different to what it was before.
Continuity mistake: When D'Amico is looking on his iPod at the picture where he sees kick-ass in the apartment (this is when kick-ass first meets hitgirl) in the next shot its a black iPhone, then an iPod again and then a black iPhone. To give more proof Apple iPhones with black casing are plastic therefore only slightly reflective but you can see on 2 shots the back is silver and reflecting light.
Continuity mistake: During the scene in Razul's apartment the placement of the boxing gloves above the punching bag changes several times throughout the scene. As Kick-Ass confronts Razul they are only barely visible from behind the bag, they switch positions several times during the fight and as Hit-Girl leaves through the window at the end of the scene, they are now on the opposite side of the bag to where they started and in full view. (00:38:05 - 00:41:55)
Continuity mistake: In Razul's apartment just after Hit Girl cuts the leg off one of the occupants, she impales him in the back and turns to Kick Ass and smiles. You can see that Hit Girl's spear is not impaled in the victim's body but is angled away from the victim. (00:39:50)
Other mistake: During Hit Girl's dramatic rescue sequence, she shoots the last two guys in the head. The man she shoots last (in the red and yellow balaclava), she aims at his torso yet shoots him cleanly through the head. It's made all the more obvious by the fact that this scene is in slow motion at this point.
Revealing mistake: In the sequence initially introducing Hit Girl and Big Daddy near the beginning of the film, where Big Daddy shoots Hit Girl in a training exercise, no bullet hole appears in her overcoat, despite her having to unzip it to remove the projectile from her bullet proof vest. In the wide angle shot, padding from the coat is see bursting into the air upon impact as she is knocked back to the ground. In subsequent shots, no bullet hole is ever visible in her coat either. (00:12:55 - 00:13:48)
Continuity mistake: At the beginning when the Armenian guy is falling from the top of the building, before he hits the car his head is pointing down, but he lands on the car back first.
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