Picard orders the helmsman to proceed at warp 6, but, when he asks Data their ETA with the Phoenix, the latter says that they are traveling at warp 4. Considering the urgency of the situation the Enterprise would not have reduced speed.
While under attack from the Cardassian ship, Picard asks to increase power to the forward shields. In the next scene, the Cardassian ship is shown firing from behind.
When Captain Picard orders Worf to continue firing phasers, you hear the sound of photon torpedoes being fired instead.
In his opening log, Picard says that a long conflict between the Federation and Cardassians ended a year previously. It's odd that this conflict was never mentioned during the first two seasons, when it must have been going on.
When O'Brien volunteers to beam to the Phoenix even though its shields are up, he explains that the Phoenix uses a high energy sensor system that cycles every 5.5 minutes, with a window of a fiftieth of a second between cycles. He thus disclosed highly sensitive information regarding a vulnerability in the shields of the Phoenix's class of starship in the presence of a Cardassian officer. Given that O'Brien earlier showed his mistrust of Cardassians, he would have been less specific in his explanation in order to avoid disclosing such information to the Cardassian.
Another of "Chief" O'Brien's mystery ranks. Previously his rank was spoken as Chief Petty Officer. In this episode, we clearly see two solid gold pips on his collar, indicating a Lieutenant's rank. He is never referred to as anything but a CPO, but his collar jewelry keeps changing.
When chief O'Brien is at the bar in 10 forward the Cardassian orders a drink. He then asks if the chief wants another. O'Brien says he does and the Cardassian orders an "ale". Unless he's telepathic how does he know what the chief is drinking? It could be a an ale or a lager or a ginger ale or who knows what wacky space drink it could be.