I just finished the season with "The Neutral Zone" and I noticed a few things:
1) In the scene on where Data returns to the bridge as the Enterprise gets to the neutral zone, you can see a glob of makeup on Brent Spiner's right eyebrow.
2) In the scene where Offennhouse is wondering the coridors and enter the turbolift, at he top of the doors you can see 2 small "peep" holes just to either side of the seam where the two doors meet
3) In the scene where Picard is talking to the Romulans on the viewscreen, when they cut to the shot from behind and above Picard facing the viewscreen, you can see Stewart's marks on the floor between con and ops.
Overall there are some odd things about this episode, particularly when it comes to security measures aboard the Enterprise. Guests seem to be able to wander around and access computers as they desire (explained as humans in the 24th century having self control). The Offennhouse is able to call the captain on a whim and just walks right onto the bridge. The kicker is that the chief of security along with at least 2 additional security officers are on the bridge and just stand there as he enters (granted they were probably distracted with the Romulans), but when Picard tells them to get him off the bridge, as soon as begins to resist they give up and 10 minutes later after he interrupts the conversation between Picard and the Romulans, when he's ready to leave, then they escort him off the bridge. Strange indeed, but overall this was a good episode as far as the Romulan plot goes.