Corrected entry: When 'present day' Picard talks to the Romulan commander, they each agree to send one ship into the neutral zone to investigate the space anomaly. But after this you never hear anything about the Romulans again. As paranoid as Romulans are, I find it hard to believe that they'd just let the Enterprise go play around in the neutral zone without keeping an eye on them. And there is no dialogue to indicate that the Romulan ship might be cloaked either; you'd think something with that kind of tactical import would be pointed out.
Corrected entry: When Picard realizes the paradox in Ten Forward, he and Data postulate that the time phenomenon began because three Enterprises in three time periods were generating the beam. However, in the future, the U.S.S. Pasteur generates the beam, not the Enterprise.
Corrected entry: OK, try and follow this - it's one of those time travel problems. The central premise of the episode is the paradox of the distortion being created in the future and getting bigger in the past - anti-time. Now, in the future, Picard gets to the location of the distortion and nothing is there - fine, makes sense so far. Unfortunately, when he returns to the same location (AFTER the first time), the distortion has appeared. If the paradox theory was run through to it's conclusion, the distortion would have been there when Picard first went to the location in the future, but not the second time.