Visible crew/equipment: When Riker first beams down he uses a flashlight - if you look closely you can see the electrical cord that runs down his sleeve to an off-screen generator.

Continuity: After Wesley makes his neutrino pulse suggestion, Picard tells him to go do it. Wesley walks off camera. Then there's a commercial break, and Wesley is back on the bridge in the long shots. A few minutes later we hear the turbo-lift and Wesley walks back onto the bridge.

Continuity: In the episode 'Yesterday's Enterprise' (season three, episode 15), watch the final scene with Geordi and Guinan in Ten-Forward. Although time and the universe has returned to normal, Geordi is still wearing the uniform from the alternate timeline (note the sleeve detail, and the extended neck piece).

Revealing: When Tasha Yar and company first enter 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.

Factual error: The second piece of music played at the concert is by Brahms and not Mozart.

Revealing: During the phaser battle on the Borg ship, a detonation wire is seen attached to the right foot of the drone that Beverly kills.