Corrected entry: When the five kids are sitting in the comic store and Katie says something about how she would "bang the **** out of Kick-Ass", we can see out the window that it is raining reasonably heavily outside. We then cut to Katie and Dave making out in the alley behind the store only about thirty seconds later, and it isn't raining.virtual-toast
Corrected entry: In the scene after Kick Ass meets Hit Girl and Big Daddy for the first time, D'Amico is examining an iPhone with a photo of Big Daddy on it. One of his goons explains that the photo is the last one the owner of the iPhone took before his death, but the screen says that the photo displayed is photo 7 of 16. If it was really the last photo ever taken, it would be 16 of 16, assuming that the goon hadn't played around with it before showing D'Amico.
Corrected entry: The newspaper headline read 'kick-ass impersonator killed' or something resembling that, but the problem is, no one knew who kick-ass actually was. Therefore they wouldn't know for sure if it had been the real kick-ass or not.
Corrected entry: When Kick-Ass calls Big Daddy and Hit Girl for help, they leave behind their hot cocoa. After Hit Girl rescues Kick-Ass and they return to their house, Hit Girl looks at the two mugs of hot cocoa and we can see the marshmallows floating in both cups. Considering the amount of time elapsed, those marshmallows should have been melted.
Corrected entry: When hit-girl is pinned down late in the film by the few remaining men and is out of ammo, she never uses the grenades strapped to her. Assuming they were any kind of functional grenade, i.e. a flash, smoke, or frag, she could have used them to, at the very least, cause a distraction well before the guy goes to get the bazooka.