Weapons firing two or more Bullets have their muzzle flashes inverted.

[tomsons26]

When the left barrel on the Heavy Tank fires muzzle appears for the right barrel, projectile is fired out of the left and vice versa. Related to initial state of the two shooter bitflag that is toggled?

gif probably needs to be dissected frame by frame to spot it easily

[LinKueiOminae]

not sure if helpful, but that bug exists in TD and TS as well.
Even the new Remaster has it (visible in the Trailer)