Bart mentions that he is "two years and thirty-eight days" older than Lisa. Bart's birthday falls on April 1st, so this would make Lisa's birthday May 9th (even though "Lisa's First Word" implies that Lisa was born around the time of the 1984 Summer Olympics). The Simpsons exists on a floating timeline, where the year of people's birth regularly changes. It's possible that finer details like the month or day of their births is also not set in stone.
When Rod and Todd are being chased by a moth, they both have Entomophobia.
When Lisa talks to Mr. Smithers at the Hospital, everyone in the queue is seated, only Mr. Smithers is standing and ashamed, for a very peculiar reason.
Bart calls for an Emergency "Sisterectomy" or as he was pranking, Sister wrecked me.
Comic Book Guy for complications after eating too many cheeseburgers
Unknown patients include:
someone with a fidgety leg
a prostitute
a hippy
The patient diagnosis form at Dr. Nick's practice lists the following afflictions:
Unusual sex practice
Looter's hernia
Mexican standoff
Prison tunnel syndrome
Armed homeowner
Allergic reaction:
Mace
Pepper spray
Bullets
Liquor store robbery
John Gotti's disease
Cultural References
The title of this episode is a play on the 1994 film Sister My Sister.
The book that Lisa is reading is a parody of The Baby-Sitters Club book series.
The man behind homer is layered in front of him
Goofs
At church, in the faraway shot the man sitting behind Homer is layered in front of his head instead of behind it. Also the man behind Bart has 1 arm and the person next to Agnes Skinner is not Principal Skinner he's an imposter.
Lisa is missing her leg
Lisa would not have been able to babysit Ralph as they are both the same age.
When Lisa unfolds the game board at the Flanders' house her leg briefly disappears.
In the same scene, an orange piece of path in the gameboard briefly turns green.
A man (third person from right) with a yellow moustache
A man at the doctor's office has a moustache colored yellow like his skin instead of brown like his hair.
Frink is seen in Dr. Nick's hospital having been involved in a scientific accident. But later, when Lisa is confronted at the Squidport by Hibbert, Frink is seen in the opening ceremony crowd.
The emergency men should know that there's no such thing as "Sisterectomy".
When Chief Wiggum and Sarah leave the house, Sarah’s legs and feet aren’t drawn.
