Larry's comb-over always faces away from the camera; when he turns his head within a single shot, his comb-over switches to the other side.
Mimsy Bancroft, the "unrequited love of [Mr. Burn's] college years" attends the Yale reunion for the class of 1914, even though Yale didn't begin admitting women as undergraduates until the 1960s-nor did Yale have a proximate sister school.
When Homer and Larry are outside Burns Manor after getting kicked out by Mr. Burns, the drink in Larry's glass disappears for a brief moment before reappearing.
In Mr. Burn's flashback to 1939 he and Lily Bancroft are kicked out of a screening of Gone with the Wind (1939), a film which did not open until open for general release until 1940.