Practically every student from P.S. 118 except Arnold, Helga, and Gerald is relegated to a minor role (which include several of the supporting characters) or a background role (which include all the other students).
Several 3D models were used in the film; for the FTi helicopters, the bulldozers, Scheck's car, and Murray's bus during the chase scene.
Big Bob's hair is shown to be brown in the movie. However, in all of his appearances throughout the series, his hair was always gray. It returns to being gray in Hey Arnold! The Jungle Movie. According to Craig Bartlett, Bob dyed his hair because he was going through a mid-life crisis.
At the end of the credits, the first song that is playing Lil' Romeo's 2-Way and is also the first single for his album Game Time. There also was a music video for the original soundtrack of the movie.
The "sneeze" sound effect in the Nickelodeon Studios vignette was originally featured in the Nintendo 64 video game, GoldenEye.
The movie's plot shares many similarities with the episode "Save the Tree"; such as Big Bob and Nick Vermicelli working together to build a new beeper emporium (and end up fighting), protests to save the tree/neighborhood being done, Arnold going to the Federal Office of Information, and Grandma hijacking a bulldozer. Mighty Pete itself also appears in the opening scene of the movie.
Before being converted into a theatrical film, Arnold Saves the Neighborhood, much like other Nickelodeon TV movies (such as Channel Chasers), was going to exist as a full 70-minute TV film and as three separate episodes, with Arnold Saves the Neighborhood, Part 3 being the series' 100th half-hour.
The movie's teaser trailer was produced long after the actual film, as it features the improved animation from the two post-movie episodes, and Arnold is voiced by Alex D. Linz, since by the time the film was selected for a theatrical release, Spencer Klein's voice had already changed. It also has Helga in the same spy outfit she had in "Married".
The police van that takes Scheck away says HCPD on the side, for "Hillwood City Police Department".
The poster for Hey Arnold! The Movie was based on the one for Nickelodeon's previous theatrical release, Jimmy Neutron: Boy Genius, with the main hero up front (Arnold, Jimmy), his friends behind him, and the enemy (Scheck, King Goobot) hovering above, reaching out to them and being larger than their actual size.
When Grandma is in the police van, she says "Put the lime in the coconut, and mix it all up", which are lyrics from the song Coconut by Harry Wilson.
After Scheck detects Arnold and Gerald in his building he says the title of the song Life is Just a Bowl of Cherries by Lew Brown & Ray Henderson.
Arnold and Gerald's spy attires are a reference to Men in Black.
While at the club with Red, Nick Vermicelli tells a disguised Arnold to "get us two more Bartletts", a very obvious reference to Craig Bartlett.
When Grandma breaks out of prison, her escape is identical to that of Andy Dufresne's escape in The Shawshank Redemption, i.e. escaping through a secret passageway concealed by a poster.
During the fight with Nick Vermecilli, Big Bob is splattered with green pickle juice, his eyes become red, and fights even harder, a reference to The Incredible Hulk.
When Scheck sings, "You'll take the high road and I'll take the low road" after he and the bus switch places, those are the lyrics to The Bonnie Banks O' Loch Lomond.
The scene of the bus clearing the destroyed overpass is a reference to this scene from Speed (1994).
When Scheck tells Arnold, Gerald and Helga, "And I would have gotten away with it, if it wasn't for that meddling football head, the kid with weird stack of hair, and that brat with the one eyebrow." This is an obvious reference to Scooby Doo, in which every episode had a criminal saying "...and I would have gotten away with it, too, if it hadn't been for you meddling kids!" A live-action Scooby-Doo film was also released at the time the movie came out.
In one of the opening shots and in the final shot, a building resembling a mix between the Transamerica Pyramid and the Empire State Building can be seen in the skyline.
In the beginning of the movie, Mr. Green being elected as city councilman in "Mr. Green Runs" is referenced, and is the reason he's aware of Scheck's plan.
A large amount of minor characters and one-shots from past episodes make cameos in the movie, mostly during the first act and at the end. Some examples include Dr. Bliss, Miss Felter, Mr. Leichliter, Rabbi Goldberg, and Torvald.
Gerald says to Scheck, "What if we were to tell you that we don't buy your story?", and subsequently gets thrown out of the building with Arnold. Something similar happened in "Door #16".
When Helga overhears Nick Vermicelli talking with Scheck through his cellphone, she's looking at a pair of Nancy Spumoni Signature Snowboots in a magazine; another callback to "Arnold's Christmas".
However, the snow boots in the magazine have a very different design from the snow boots in that episode. It's possible they're just a new edition of the boots.
Ever since "Dino Checks Out", Ray Doppel has been relegated to playing in small clubs, and has formed a band called The Raytons.
The poster in Grandma's cell hiding the secret tunnel is the cover for one of Dino Spumoni's records, which previously appeared in "Dino Checks Out".
The "flying stars" effect that first appeared when Harold got hit in the Pilot episode and was reused several times over the course of the series (most notably in "New Bully on the Block") is reused in the movie.
Helga's attire for her "Deep Voice" alter-ego consists of her wearing a trenchcoat and fedora hat. She also dressed this way going to her first session with Dr. Bliss in "Helga on the Couch" to try and be inconspicuous (though Phoebe recognized her right away), albeit without the stilts she also used for her "Deep Voice" disguise to appear taller.
Arnold's video editing skills from "Freeze Frame" come into play once again.
During the film's climax, when Harold leans out of his bedroom window to witness the explosion, his Wally doll from "Ransom" can be seen under his arm.
The bulldozer driver Grandma throws out previously appeared in "Summer Love".
Grandma learned how to drive a bulldozer in "Save the Tree".
Stinky is seen wearing his shirt from the pilot at the end of the movie and on the cover of the book adaptation.
This movie was focusing on Arnold, Helga and Gerald, precisely the same 3 characters from Hey Arnold! who appear in The 12 Days of Nickmas.
