This episode has no couch gag. Instead, it has a "Previously on The Simpsons" montage with never-before-seen-stuff because it does not fit in with any other episodes.
It was originally promoted as being the 400th episode but aired as the 399th.
The information sheet on the three missing students reads: Jimbo: Full name: Corky James Jones; Known aliases: Jamesso, Dr. J, Hector Gutierrez; Last known location: Duff Gardens log flume (middle seat). Dolph: Full name: Dolphin Starbeam; Speaks: Spanish, German, Hebrew, Arabic, Korean,Latin, Old English, Klingon, Esperanto; Friends with: Jackie Chan (unverified); Special skills: Horse riding, tap dancing, British accent, stage fighting. Kearney: Full name: Kearney Zzyzwicz; Prior offenses: Indian burn (3rd Degree), full moon, half moon, attempted purple nurple, hertz donut (acquitted); Owns own tuxedo.
The upside-down newspaper Milhouse is holding is the Springfield Shopper. The headlines read "Mayor's Breath Still Problem", "Corn Less Popular" and "Bake Sale Today".
Jimbo Jones cellphone's ring-tone is the theme to the movie and TV show "The Odd Couple".