Okay, so an interesting bit of trivia that the Infinity Train minisodes gave us is the corresponding numbers of multiple cars, of few which we’ve seen, or will see, in the actual show itself. I’ve listed the numbers ascribed to each car accordingly, in the order of when the videos were released;
Green Car: 1
Tiny Wizard Car: 4,598,200,004
Kaiju Inexplicable Earthquakes Car: 21,486
Beachside Car: 1,221,121
Snow Car: 126,186
Hill Car: 89,100,034
Movie Theater Car: 91XSD
Cross-Eyed Ducks Car: 60,790
Minecart Car: 602,214,179
Wedding Cake Car: 51,413
It seems that the order of the cars have been shuffled by the time Tulip arrives, as she encounters the Tiny Wizard Car (which is numbering at about 4 billion) BEFORE she enters the Beachside Car (at ~1 million). Presumably, the cars are listed in order of creation; However, the numbers are revealed as ‘Train Documentary #’, so it’s also possible that OneOne is listing the cars in order of current sequence, rather than order of creation, and the minisodes aren’t in chronological order.
This means the Green Car is either the first car ever made (aside from the front of the Infinity Train, which could be #Infinity), and/or the first one encountered. Of note, the deer-shaped hole from Dracula was also there, so that means Dracula either caused havoc in the car directly behind OneOne, or did so while the Green Car was in another position from a previous shuffle.
We know the Infinity Train has at least a little (comparatively speaking) over 4 billion cars, not counting the original engine. However, the Movie Theater Car is inexplicably listed as 91XSD (and OneOne says it like that, too, so it’s not a misspelling or anything). Presumably, XSD is meant to indicate that the number of cars is so high that OneOne’s had to resort to letters to help keep track of the higher-numbered cars; Which, if we take 91 to be the first two digits of the car’s sequence, means that there are, at the very least (this is the most conservative number possibility), 9,198,200,004 cars on the Infinity Train. However, because that’s the same number of digits as the Tiny Wizard Car’s designation, it’s likely that XSD indicates WAY more digits than just ten.
Now, getting into really mindless, pointless, overthinking speculation that is DEFINITELY not canon and analyzes very clearly not-intentional letters, if we look at latin numbers, XD hypothetically means 490 (this isn’t how 490 is supposed to be written, it’s actually supposed to be CDXC, but this is just a for-fun part and not meant to be taken seriously). S isn’t a number in Latin, but ignoring that and assuming 490 is at least what XSD means, this leaves two options;
A) 91XSD translates to 91,490.... But this is a comparatively small number and OneOne has no reason to shorten it with code as a result...
OR more likely...
B) 91XSD translates to 9.1 X 10^491. And that’s a number WAAYYYY past googol, and thus a worthy requirement for shorthand abbreviations.
Mind you, the meaning behind XSD without a doubt has no actual intended meaning and I’m just overthinking this, but if we really wanted to have fun, then this is the number I propose. This means the Infinity Train, appropriately, has at least 9.1 X 10^491. So, yeah- That’s a lot. Mind you, this is all ignoring S in XSD, which could mean 10S500, and whether that means there are ten digits followed by the number 500, or 10 before 500 digits, who knows? In all honesty, it doesn’t even matter.
(But just in case; S in XSD can indicate it’s either Car 910,000,000,500 (two digits more than Tiny Wizard Car’s designation of about 4 billion, and two digits less than the estimated $ worth of all the physical dollars, notes, and coins in real life), OR it’s Car 911.0 X 10^501)
Basically, the max number would look this;
91,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000... (with about five times as many zeroes as actually depicted)
