Hard Bargain - S1-E9
Other mistake: When one of the kidnappers knocks on Michael's door, it shows him undoing a sliding barrel bolt before opening it, but the bolt does not have anything it slides into on the door frame rendering it pointless, especially as the door opens inwards. (00:30:20)
Old Friends - S1-E3
Other mistake: This Jan Haseck assassin, who has either multiple allergies or else one allergy to a very common substance (peanuts), could never do any espionage work, as it would make him too vulnerable.
Chosen answer: It might not actually have one, in which case, he'd have to go down into the club and use theirs. As for showering, going to his mother's house or a gym membership would take care of that.
Captain Defenestrator