Arnold's parents are named Miles and Stella, but this isn't revealed until much later, in "The Journal", which is an extended story about them.
Animation cels from the episode (such as the one to the right) indicate that there was a scene where Helga hugged Brainy; this scene is not present in the actual episode.
The flier Mr. Simmons hands out says "PARENTS DAY" on it, but it's always referred to as "Parents Tournament Weekend".
Big Bob cruelly calls Arnold "Orphan Boy". In purely legal terms, however, a child may only be considered an orphan in the event of death or disappearance of, abandonment or desertion by, or separation from both parents.
Grandma refers to Grandpa as "Anjin-San" while cooking in her karate outfit. This is a nod to the main character in James Clavell's novel and TV miniseries Shogun, John Blackthorne, who is also called “Anjin-San”.
The character Dr. Iron Claw, that Grandpa invents while telling Arnold the story of how his parents met, is a possible reference to the Inspector Gadget villain Dr. Claw.
Miles' use of the phrase "aye-aye-aye!" after falling down the cliffside is most likely a reference to The Gods Must Be Crazy, wherein a similar character frequently uses that phrase.
Baby Arnold wears a light blue shirt and diaper: the same attire as Tommy Pickles in the Rugrats franchise.
This episode was produced at the end of Season 3, but was held over for about a year and a half, airing in 2000 as part of Season 5 in the US. However, this episode did air as part of Season 3 in several other countries, such as the U.K., where it aired in December 25, 1998. While the exact reason for the delay is unknown, it is speculated that Nickelodeon planned for this episode to serve as a lead-in to the planned Hey Arnold theatrical movie (similar to how The Rugrats Movie and it's sequel had an prequel episode), but was ultimately turned into a Mother's Day/Father's Day episode (as proven by its May 10 airdate), and another "prequel" episode was later ordered. Nowadays, this episode is aired as part of the regular rotation of episodes, and isn't considered a holiday special.