The German dessert "mon streusel" was a running gag on set - it is mentioned a few times in the movie and no one including the writer really knew what it was until the movie had been completed.
Kevin Troy's character Carl and Paul Wiedecker's character Pastor Kevin ad libbed several small sections of the movie together when the scene was decidedly in need of a bridge from one point to another. This can be seen when they enter the Church after the story and when they meet for the first time.