Here's one I've forgotten to address: when you grab the invisibility powerup and throw dynamite one by one constantly, you can keep throwing dynamite as its ammo counter reaches negative values. This only happens in primary fire and not secondary.
I tested this on E1M1 in the room where you get the invisibility powerup for the first time. Also on E1M2 where you get the invisibility powerup after a slam dunk with the basketball hoop and then you eventually get five dynamite. Seems to happen in every level. The powerup is bugged with the dynamite, but thankfully, the other weapons are not affected.