Factual error: In the scene where Anna is standing with George beside his father's GTO, Elaine suddenly runs in and pries her away from George. Elaine and Anna get into the cab. As the cab pulls away, the side door is marked as an NYC cab with a taxi license number, etc., but the license plate in the back is a California plate.
Mush-Rumors - S1-E17
Factual error: When Mario and Luigi jump into the water, the car is reflected in it but Mario and Luigi are not. (00:07:30)
Honoria Glossop Turns Up (or, Bridegroom Wanted!) - S4-E3
Factual error: Sir Roderick has moved his psychiatric clinic to New York because the BMA wouldn't approve of his methods. Although we don't get exact dates for the episodes, since prohibition was in effect in the last episode and Puttin' On The Ritz came out in December of 1929, we can presume it's about 1930. The AMA wouldn't recognize psychiatry as legitimate medicine until 1945. Sir Roderick wouldn't have had any better luck in America.