In the scene where Dale goes to spend Bill's fake check for a million dollars his shirt sticking out of his jacket disappears and reappears repeatedly.
Assuming Ernst the hairdresser is of German origin judging from his first name and accent, his doormat reads "wilkommen". This is a classic error often made in movies in the English language. It's spelled "willkommen" - with two "L".
Why would bobby ask if the living room couch was ever an outdoor couch? the entire house, including the furniture, was cleaned like two years ago.