Stupidity: When Matt goes to the bank to close out the account he learns that it's been closed already by Kelly. Matt says he will be expelled, but he never did anything wrong except lie about who Kelly was. The bank teller is the one who was flirting with him and gave him the money with out any proper ID or papers, so if anything the bank would reimburse Matt/the school.
Stupidity: Vincent's choice to cut the power to the building that Annie is in does nothing but waste enough time for Max to save Annie. It would have been easier just to go up to kill her and he probably would have gotten away from the police if he did so.
Suggested correction: It also slows Annie and Max down by forcing them to walk in the dark, and also, at this point, Vincent is really torn up from the crash, and the mere sight of him is going to make Annie very suspicious or even afraid, unless the power out (which for all she knows is just from the building) gives him a plausible reason for being so mauled.