While this episode takes place around 2005 (though the episode itself didn't air until 2006), it is made explicitly clear in Recess that the show takes place over the course of the 1997-1998 school year, with Recess: Taking the Fifth Grade taking place at the start of the 1998-1999 school year.
Moral: Work can also be fun if you try to find a way to make it so.
This is the only time Nani appears in a crossover episode.
There are a few moments between T.J. and Spinelli, like when he asked her to help him out with distracting the experiment Lax. Also, when the six kids plus Lilo and Stitch were all at the observatory, right before the two of them both get zapped by Lax, Spinelli is seen quickly taking T.J. by the hand and then running up together to the rooftop of the building. After that, they are both seen goofing off together on the beach, while under Lax's spell.
The Recess Gang are the only characters from a One Saturday Morning show to appear in an episode of a Disney Channel series. Also, this marks the final appearance of the Recess Gang on television.
Because the only teacher appearing in this episode is Miss Finster, as well as Miss Grotke neither being seen nor mentioned, the gang was probably still in the fifth grade in the episode.