I don't know if there was an adequate tech rehearsal for the masquerade or not. I know that unlike Worldcon where the masquerade can often hold the space for most of the day to do the rehearsals, ComicCon has to use the large space not only for masquerade but also for the big panels. While there was a 2.5 hour break between the last panel and the start of the masquerade, some of this time was eaten with clearing the room and then filling it. With a 2 hour show, that would make doing a full run-through in the space difficult on Saturday.
But even taking into account that there may not have been a run-though, the tech work was pretty shoddy. Most obvious to someone watching the video -- but also anyone watching where they could only see one of the big screens or in a remote viewing area (so more than half of the people actually watching live as well) -- was that the cameras were regularly in the wrong place. Also the video director didn't have an idea of when he (or she) needed wide shots and when they needed close shots on some of the larger groups.
However, there were also quite a few missed lighting cues -- mostly blackouts at the end of the bit that left the performer standing at the front of the stage expecting to be able to walk out without performing. At first I thought that the follow-spot operators weren't doing all that well, and then I realized that the cameras weren't positioned all that well in relationship to the follow-spots, which left a couple of the performers in the dark to the cameras but probably OK to the live audience.
There was also one costume that needed to have a black scrim behind the performer to really work well, but the scrim was instead lit with a backdrop -- allowing the performer to be seen breaking some of the illusion the costume (a walker from Return of the Jedi).
The music and sound cues were mostly good with perhaps one or two glitches.
I suspect that all of these problems could be helped by a full run-through, but it would have had to be done on Friday or even Thursday -- which in turn would have required moving a couple of items to the other large hall or elsewhere which might not have been doable. But I'm sure that they could have set up space on Saturday somewhere in one of the nearby hotels that would be big enough to simulate the stage and back stage areas, and enough audience for the tech people to at least observe and take notes to refine their cues and shots.
The lighting cues could also be helped if the performers had written out clear directions that say something like "when I come front stage and bring the sword down, black out lights," so that the light operator could at least have something to work with.
Having done, or observed (in the case of video directing) all of the jobs -- but in venues other than a con masquerade -- I can appreciate out how difficult it is to do without a rehearsal. But the con needs to do something or it will distract people like me who will spot this kind of stuff.