The song everybody sung, while Sherri and Terri saw a skunk in a cookie box (except Sherri and Terri since the twins are chased by the skunk), is a parody of Jingle Bells.
The watermark that says "Only You can Prevent test fraud" references Smokey the Bears famous quote.
When Homer draws a picture of himself it looks similar to his original look. Originally, Homer was going to have a G for his ear and the M on his hair and it would form Matt Groening's initials. However, as explained in audio commentary for "Lost Our Lisa", the design was dumped as it would be to distracting for fans.
The last time Ralph cries after he is called a 'little freak' occurred in "Bart Sells His Soul".
The last time Lisa imagined herself fat and being with a boy who has a crush on her and denied the fantasy happening was in "Lisa the Simpson". This is also the last episode where Lisa was concerned about her Simpson DNA.
Lisa was concerned about her butt being big was in $pringfield (not wanting to dress up in a state of Nevada costume) and "Lisa's Date with Density" (Nelson told her that it stuck out).
Second episode where Marge brings a kid she bonded with to the Simpson house, much to Bart's dissatisfaction. First was "This Little Wiggy" which in that episode it was Ralph Wiggum. In this episode, it is Nelson Muntz.
The scene with the State Capital test is very inaccurate. First the test left out Arkansas so the the Capital of California is Little Rock, which is the Capital of Arkansas. The Colorado Capital became Sacramento, Califorina's Capital and the Colorado Capital became Denver. Then the answers merged closer making it the same as it should be. The final problem is when Homer claims the Capital of Kentucky is not Frankfort. The Capital is Frankfort. The problem with it is that Kentucky is not on the One Page quiz. This is because the quiz only goes to Iowa.
When Sherri and Terri are running away from the skunk, Terri has a purple hand.
Homer drew a simple black and white sketch of himself, but when he talks to Lisa, his drawing is colored.