The Unfinished Projects

Over the course of Infinity Train's run, plans were made for a total of eight seasons, or "books", of the series, as well as various spin-off media. Due to the various corporate changes at Warner Media, including the Warner/AT&T lawsuit and the eventual merger with Discovery, few of these made it beyond the planning stages.

Scrapped episodes

Infinity Train episodes were drafted by the writing team via "premises": heavily detailed outlines of episodes with story beats to hit and events that could happen. These premises were then revised before a member of the writing staff would write an actual script. Notable examples of episodes that did not make it past the planning stage include:

The Bliss Car (Book One)

Main article: The Bliss Car (scrapped episode)

The original series premiere was an episode concept called "The Bliss Car." The unused premise includes some of the same story beats, such as Tulip boarding the train and running away from the Ghoms, but is markedly different from the finished episode "The Grid Car." Most notably, Tulip's impetus for running away is learning of her parents' divorce (the scene depicted in "The Cat's Car") and the first car she arrives in is a train car full of passengers staring at television screens (reused via the Memory Tapes).

The Mall Car (Book One)

Main article: The Mall Car (scrapped episode)

In the original pitch for Infinity Train, the sixth episode took place in a Mall Car inhabited by potato people coming out of a mannequin's chest. One-One would have been kidnapped and replaced by a cowbird (a parasitic bird) egg. The concept was scrapped because it had little to do with Tulip's emotional journey, and was replaced with "The Unfinished Car." However, the series would eventually feature a Mall Car and a parasite in Book Two - Cracked Reflection.

Christmas special

This special episode would have featured The Cat as a host for a 60s variety TV show potentially sponsored by the Wisconsin based fast-casual chain restaurant Culver's. In the Book Two DVD commentary it was said to feature the return of multiple characters from throughout the series run, including Perry. According to Lindsay Katai, the planned writer for the episode, the Christmas special was supposed to be the last episode included in the team's "season one" contract of Infinity Train, which included Books 1-4 and the unfinished Book 5. Reportedly, it never made it beyond the brainstorming stage before the team was laid off. Both Katai and Owen Dennis have voiced it would have been "crazy" and was the project they most wished they were able to make.

When asked about the potential return of the Fart Car from the pilot during a Reddit AMA, Owen Dennis claimed they would include it in the Christmas special. It is unclear if Dennis was serious, although at the time he made this comment (August 26, 2020) the show was still in production.

Scrapped seasons

Owen Dennis planned for Infinity Train to run for a total of eight books (a reference to the infinity symbol) and the writing team drew up outlines for these eight books. With the notable exception of Book Five, very little development was done beyond these outlines and it is not entirely known what these seasons would have entailed, although Dennis and the team have dropped hints since the conclusion of Book Four - Duet.

Dennis has previously defined each book by a particular keyword: Book One was a mystery, Book Two was an adventure, Book Three was a tragedy, and Book Four was a comedy. For the unreleased books, he revealed that Book Five would have been about grief, Book Six about guilt, Book Seven about revenge, and Book Eight about acceptance.

Book Five

Main article: Book Five

Book Five was planned to be a film that documented the exact nature of Amelia's takeover of the train, which is only briefly hinted at in Book Four. Set in the late 80s with the plot running parallel to the events of Book Four, the planned film only made it to the script phase with a few conceptual storyboards, the latter of which were leaked in early 2021. Cartoon Network Studios passed on the film believing that its focus on an adult woman grieving for her partner did not have a "child entry point." Dennis has expressed the belief that this is the unreleased book with the highest chance of eventually being revived and produced due to how far it got in the process.

Book Six

A little less is known about what was planned for Book Six compared to Book Five, but a general idea can be discerned from hints given by the production crew over the years. The season was planned to take place during the early 2000s and would have followed a new character never introduced previously. Dennis wanted to explore the anxiety he recalled of growing up during this era, particularly in the aftermath of the September 11 terrorist attacks. In Dennis' interview with Comic Book Resources, he noted "I see a lot of parallels to what I experienced as a teenager at that time to what teens and younger people are experiencing right now." Adding to the theme of guilt for this season, Dennis wanted to explore the idea of guilt over something that both is and is not one's fault.

Following the cancellation notice over Book 5's lack of a "child entry point" the team threw together conceptual artwork for Book 6 in a last-ditch effort to convince HBO Max to renew the show. One of these images, created by Madeline Queripel and titled "Blake.png", was eventually released online during an Instagram AMA by Owen Dennis in 2022, depicting the potential protagonist for Book 6, Blake, with a potential companion denizen. Dennis noted in the AMA that the image does not necessarily depict events from the season, but rather a tonal concept to give the executives an idea of where the show would go, and also that it still had a "child entry point." Ultimately, the team was never given the chance to pitch the planned season.

While this season never made it to production, Dennis has expressed interest in using the setting and themes in a different television series if given the opportunity.

Books Seven & Eight

The crew has not revealed their full plans for the final two books, although they have shared some information about planned story lines.

• Amelia and Hazel were slated to return at some point, and their relationship as creator and creation would have been explored.
• Book 8 would have touched upon Alzheimer's Disease, inspired by a book Owen Dennis's grandfather wrote about slowly succumbing to it. A full final episode script was written by Alex Horab and is on one of Owen Dennis' hard drives.
• One of the planned books would have centered around an older Tulip.

Other season ideas

There were many emotional and personal issues Dennis wanted to explore. A few mentioned in Comic Book Resources includes: addiction, having a child, relationships and consent, and generational trauma. Some season concepts that the team have thought of during development include:

• Two people talking across dimensions and living out of phase with each other.
• Someone falling in love with another based on their tape.
• Someone trying to catch the train to study it. This was the concept most likely made into a season.
• Someone getting on the train multiple times due to shock from being out of the real world and away from their family for a couple of years.

Spin-off Projects

These plans were scuttled due to the delay in Warner Media and AT&T's merger (which also delayed Infinity Train's release on HBO Max).

• A VR game where the player would travel around Corginia and solve puzzles. Dennis notes only 10 people got to play it.
• A choose-your-own-adventure novel. In a Twitch stream, writer Alex Horab mentioned that they would have been in the style of old sci-fi novels such as Doctor Who and Star Trek. A slightly off-canon story line. This was pitched very early on and was never picked up.
• Various comic books made by artists outside of The States was also one of the crews earliest pitches never picked. The idea would have expanded the anthology format and helped in creating unique stories with an international perspective.