Nice screencap, Mytran
! Unfortunately we don't get a better look at the "2", but it's obviously there.
Judging by the torpedo bay arrival scene there is an outer section and/or corridor between the actual loading bay and the outer hull (the "airlock"). While the Reliant's
starboad phaser cut the port side open, it apparently didn't cut all the way into the loading bay, but possibly destroyed the port side launcher cooling system
and one phaser beam also drilled a hole into the loading bay, spraying highly inflammable gas into the area which ignited. Thus the damage seemed bigger than it actually was (or was it just the oxygen supply of EVA suits closeby?).
Of course the torpedo gunners sitting at their bow consoles were killed or severely injured which at least could also explain Chekov's manual override torpedo firing joystick on the bridge
. That didn't look like standard torpedo firing procedure to me.