Continuity mistake: This episode comes a couple of episodes after the audience is already aware of Mr. Drummond marrying Maggie. Maggie and her son move in to the Drummond household making for a cramped living situation. Arnold shared a room with Sam (Maggie's son) and Willis got moved to Pearl's room. In this episode, there is no mention of Maggie it her son. Arnold and Willis seem to be sharing a room yet again. When Kimberly remarks about moving out, Willis and Arnold gush about how great it would be because then each of them would have their own room. Later on in the episode, Pearl is cooking for the three men stating she cooked too much because she had to get used to not cooking for four people. That's kind of an awkward statement to make being that Mr. Drummond should be married to Maggie by this episode.
Suggested correction: Season 6 was plagued with episodes airing out of order. "The Boyfriend" was actually the 14th episode produced (production code 614), even though it was the last episode of the season.
Continuity mistake: By this episode, Mr. Drummond has already remarried Maggie. Maggie and her son have moved in and Arnold and Sam share a room, where Willis has a room elsewhere. In this episode, there is no mention of Maggie or her son. Willis is back to sharing a room with Arnold. In fact when its decided that Charlene will stay, Arnold makes a joke about the bathroom saying that Kimberly won't be the only girl in the house (what happened to Maggie?).
Suggested correction: Season 6 was plagued with episodes being aired out of order. "The Houseguest" was actually the 12th episode produced (production code 612) and comes before The Wedding episodes (production code 620 and 621).
Continuity mistake: When Arnold has his picture taken for the newspaper he is wearing a red jacket however in the next scene with Mrs Garret holding the news paper he is wearing a checkered shirt.
Suggested correction: First of all, he probably took the jacket off when he got home, Second, he's not wearing a checkered shirt it's yellow.