In the flashback when Jimbo puts Bart's head in the toilet, Bart's shirt is light green (rather than the usual orange). So it is likely that these are younger versions of Bart and Jimbo.
When Dolph says, "That chick's messin' with our minds!", he sounds like Jimbo (similar to season one's "The Telltale Head" where Dolph was voiced by Pamela Hayden using the voice she would use for Jimbo Jones while Jimbo was voiced by Tress MacNeille using a higher version of the voice she would use for Dolph).
According to Bart's phone call to Moe's Tavern, the Simpson family's original address was 1094 Evergreen Terrace, rather than 742. These were the episodes before 742 Evergreen Terrace was established as The Simpsons' address.
When Moe comes into the Simpsons' house and scares Jimbo, Bart is missing most of his torso.
At the beginning of the episode, the moose loses its tail for a frame.
At Moe's Tavern, in the scene where Homer and Captain McCallister are holding their beer, the latter's eyes are both fully open.
When Homer is relaxing in the kiddie pool, one of the blue dots turns purple for a frame.
