Factual error: Lucas is constantly twirling the rifle after rapid firing a few shots. Since the cocking ring is set on semi-automatic, the rifle should fire as it comes around.
Suggested correction: He twirls the rifle in the opening of the show, after he's just emptied it completely.
The original comment doesn't state the beginning of the show. This does happen throughout the series.
Quiet Night, Deadly Night - S5-E4
Character mistake: Nils is playing checkers with Mark. Nils calls him "Mark" then "John." (00:20:35)
Suggested correction: He says "now", not "John." After he Mark says he remembers it like it was yesterday, Nils says "go on, it's your move now."