Other mistake: In the scene at the Peach Pit where Rush tells Steve that he is his biological father, he shows Steve a copy of the birth certificate. Under adoptive parents, it lists Sanders, Rush and Sanders, Iris. Only Iris isn't Steve's adoptive mother, Samantha is. Iris is Dylan's mother who lives in Hawaii.
Other mistake: The tenant board member tells George that Mr. Eldrige in apartment 8C has decided he wants the new apartment. However, the new apartment in question has a 3-digit number - 808 I believe. This indicates that the building would not have single digit numbers and letters (Such as 5E, 8C, etc.) as part of its numbering system.
Other mistake: When Tuppy goes to turn off the burglar alarm for Wooster, it's behind a hidden panel with a sign saying "Alarm Switch" above the panel. Why bother putting the switch behind a concealed panel if you're then going to label it? (Unless you're doing it for a viewing audience). (00:35:00)