Revealing mistake: Clear use of a stunt double for Avery Brooks during the brief tussle with Dax in the holding cell.
Other mistake: During the battle near the end of the episode, Sisko is heard saying, "Locking onto the lead ship" but he gives the firing order to Bashir, who is seated at the helm. This implies that the targeting controls and firing controls are at separate stations, which makes no sense.
Plot hole: Earlier in the season, it was established that The Jem'Hadar are genetically engineered to be loyal to the Changelings, meaning they will not deliberately harm them. With that in mind, the Changelings still care about Odo's well being despite his refusal to return to them. So why didn't the Lovok Changeling send a message to The Jem'Hadar ships to inform them that a Changeling was going to be on the runabout? Given that he took time to offer another chance to return to his people, you would think he'd take time to make sure he returned to the station safely.
Suggested correction: Maybe The Jem'Hadar were trying to disable the runabout to try and capture Odo and Garak.
Visible crew/equipment: As the Defiant tries to contact the Ulysses, the camera pulls too far back at Odo's station, and we can see the microphone along with the boom pole above the captain's chair. (00:14:40)
Plot hole: Thomas Riker is able to steal the Defiant partially because he's a genetic double for and not a clone of Will Riker. Thomas Riker's existence is not a secret. Star Fleet is aware that the first officer of their flagship has a genetic duplicate who resigned and is out there somewhere. There should be something in place to verify Will's location before giving Thomas access. But then, of course, we wouldn't have an episode.
Suggested correction: At this point Thomas Riker is still a Starfleet officer. There is no need to lock him out of accessing the Defiant's systems as he is considered just as trustworthy as Will.
It's said that he resigned over suspected Maquis sympathies. They were right.
They say that he had expressed political opinions that supported the Maquis, not that he had resigned from Starfleet. A large number of Starfleet officers supported the Maquis' intentions, but still stayed loyal to Starfleet.
No, Thomas Riker accessed the Defiant under the guise of being Will Riker, and Major Kira released the lockouts being under that impression.
Exactly. NOBODY in Star Fleet has thought "Well, what if one of them claims to be the other? How do we tell them apart?"
Continuity mistake: When Jadzia tells Benjamin she is going to do helioscismic measurements of the sun, the camera shifts in mid-sentence. In the first shot she is rubbing her hands in front of her, in the second shot, her hands are clasped behind her back. (00:15:20)
Other mistake: When the Klingon, Kozak, falls on his knife during his fight with Quark his blood is a deep red. It should be pink like any other Klingon. (00:02:20)
Suggested correction: Klingon blood is only shown as pink in the film Star Trek VI: The Undiscovered Country and in the series Star Trek: Discovery. In the case of the former, the blood was shown as pink/lavender to have it appear alien and also to avoid rating issues (that much blood would have given the film an R rating). This is an inconsistency in the entire Star Trek universe at large, or perhaps only in those two stated instances, and not a mistake in this particular episode as the number of times Klingon blood has been red greatly outweighs the few times it has been shown as pink.