Visible crew/equipment: When Hal rebuilds the track of dominoes, he walks out and slams the the door. This starts the dominoes falling. When it comes up to a shot of the American flag in dominoes, if you look closely to the left of the screen you can see a hand pushing it over.
Other mistake: In this episode Malcolm's new teacher begins a league table for the Krelboyne class, and since Malcolm shows that he is better than the whole class, the teacher creates a new highest rank for him which he calls "1 to the 11". However mathmatically, "1 to the 11" is still 1, so it seems rather strange that the teacher would go the trouble, and that none of the class would notice this.