Continuity mistake: During the scene when Michael is attempting to deceive Brennen into letting him and Nate go (from the time Brennen receives the picture message to when Brennen leaves), Brennen's necktie (right below the knot) changes from having a dimple to being flat, 6 or 7 times during the scene.
Continuity mistake: When Michael's mother is arrested, we see the cuffs go on with her bracelet nearer her hands than the cuffs. The shot changes and suddenly her bracelet's further up her arm - no way it could have moved there past the cuffs.
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