Corrected entry: When Tasha Yar and company first exit Ten Forward in the alternate timeline, watch through the doors as they open. An extra can be seen stood still in midstride in the passageway, before nervously noticing that the doors have already opened and that she has missed her cue to begin walking past. She then begins purposefully marching down the passage.
Corrected entry: Throughout the episode, Lt. Richard Castillo wears a Type 2 phaser, which was seen in Star Trek II. He should wear the phaser introduced in Star Trek V, or any phaser consistent to the timeline. The movie [ST V] and the episode were shot in the same year. The old phaser is clearly visible in the sickbay scene at 18:18.