Why did it have a Cannon on the front?

Me.

Oh Calabi–Yau Caboose

It's to alter reality so it can make track on which to rode on.

Neverending Railroad Vehicle

Then how did the train keep working for decades after the cannon was removed?

Ouroboros's Iron Horse.

there is no canon on the Big train. there is only canon on the earth realm when the small train arrives to pick up passengers.

Nonstop Thomas

CLICKETY CLACK DOWN THE TRACK! It's Lots and Lots of Trains!

Forever Chugga Chugga

What is this show even about? I remember liking the pilot but hated the redesigns when it got picked up.

People have problems and go on the chooo chooo to work though them.
The problem with putting people with problems on the train is that the people exploit the train and fuck about.
The things that kill you on the train are vampire monsters and other humans who also abuse the sentiant constructs of the train.

It's actually quite good. First season is about figuring out what's all that about and the protagonist figuring herself out too. You get over the redesign quickly.

It's possible to see it on kimcartoon.to or thewatchcartoononline.tv, but it's bette to see it on HBOmax if you can, so you can support the show.

ongoing choo choo

Am I blind? Where's the cannon?

Boundless Boxcars

the canon opens a portal to the real world, how else should the train pick up passangers?

It's not on the Big Train, only on the small train picking up passengers.

There is no cannon. OP either confused the headlight or the rising car coming out of the engine to be a huge gun.

It's on the real world version of the engine.

There's one on each side

got me