Looking for an anime.

No.12793189 ViewReplyOriginalReport
I need help /a/, I'm looking for an anime I watched a long time ago. I'm not sure if it was exactly a Japanese animation but it most definitely was animated. It was either a movie or a very short series, and I can't remember much of it.

All I can actually remember was a gigantic red cannon within a building that a bunch of guys were preparing and loading up throughout the whole thing. I forget if it was even fired. That's all I can really remember. Very vague I know, but if anyone has any idea what it is or might be it would be greatly appreciated.

Pic semi-related.