That Workbee that emerges from whatever-it-is cleverly does so while someone is passing in front of that part of the ship, to disguise that it's definitely not a door and it's definitely not open. You can get a pretty clear look at the detail on the neck in
this photo (I remember one that's even closer, but that's clear enough). It seems to be a stacked pair of cones, a bit like the phasers on the
Reliant. (Please, please don't let this start a debate over if the cones on the ends are the phasers, or the nubbin on the side.) The certainly could be phaser banks. The fact that they're a bit blocked by the lower saucer wouldn't matter, since the
Reliant's could fire off-axis (assuming the beams came out of the tips of the cones,
which they did).