When we last saw Happy Peppy Gary and Betty, they were being taken away in Mark Chang's spaceship in Totally Spaced Out. There is no explanation for how they got back in this episode, other than presumably that Timmy wished them back and unwished their memories of the event to prevent any problems.
When Pops made the license plate that said "SO_LONG" and "SUCKERS". Both of them reached the legal maximum limit for characters on a license plate, 7 each.
It is reavealed that the other babies are very smart.
Francis will try to hurt anyone of any age, baby or not.
In German, the episode is titled Bebe für ein Tag, meaning Baby for a Day.
Dragon Ball GT- Timmy turning back into a baby is a reference to Dragon Ball GT where Goku was turned into a kid
The only difference is in this episode, Timmy wishes himself back into a baby to avoid Francis. But in DBGT's case, by Emperor Pilaf's accidental wish
Rugrats - When Gary says "It looks like our rambunctious rugrat doesn't want to nappy wappy". He calls him "Rugrat" which refers to the title. Also, Pops' line "So long suckers" is the catchphrase of Angelica Pickles.
Disneyland - Timmy says "The Dumbest Place on Earth!" which makes a reference to Disneyland' catchphrase "The Happiest Place on Earth!".
Pops the Adult, the old man at Camp Learn-a-Torium says that he was dropped off there 60 years ago and his parents never picked him up, but Flappy Bob is only thirty seven and did not create the Learnatorium until after college. Also it's never explained why Betty and Gary force Pops to remain at the Learnatorium as he's over eighteen and no longer their responsibility.
When Timmy first finds the place in the license plate maker where you stick letters in, there were 7 slots, but later when we see him spelling "I wish I was ten", there are 12 slots, enough to fill in that sentence, without the spaces
Happy Peppy Gary and Betty punished Baby Timmy because they were nearly eaten by gators, but how did they know that Timmy (an infant) was the one responsible for them ending up in the everglades? Timmy could not have said it out loud clearly due to being a baby and there is no way they could have seen what the message with the blocks was since they were too far to read what Timmy was saying with the blocks.