When Chief O'Brien is working in a Defiant Jefferies tube, about 10 minutes into the episode, he hears noises and starts to go up the tube, leaving the panel he was working at open. He looks back the way he came a moment later. We see down the Jefferies tube, but panel he left open is no longer open.
This is the only Star Trek episode to reference a full-time forcefield being placed around the warp core to contain radiation. There are a number of other episodes (both DS9 and other series) that show the warp core not having a force field around it, as they have crew members physically touching the warp core casing. Other episodes and movies do show force fields being placed around the warp core during emergencies to prevent or contain damage, but they were not on full-time. Plus there are several times where it is mentioned that warp cores are made from a material that contains the radiation from the antimatter reaction and shields the crew from it.
At roughly 3:40 Captain Benjamin Sisko orders O'Brien to put in a full complement of "photon torpedoes". At this point in the Star Trek time line photon torpedoes are obsolete. The Defiant doesn't carry photon torpedoes. The whole of Starfleet's ships have been replaced with quantum torpedoes.
This is not correct, the Defiant was the first starship equipped with quantum torpedoes, at this point they are still considered experimental and the Defiant is the only ship in the fleet with them, but she is also equipped with photon torpedoes. Sovereign-class starships like the Enterprise-E are the next class equipped with quantum torpedoes, but she also carries photon torpedoes, at this point most ships in the fleet are equipped with just photon torpedoes. For example during the opening battle with the Borg cube in Star Trek: First Contact (1996) (which is over a year after this) there are several ships seen firing photon torpedoes, the upgrades DS9 receives in The Way of the Warrior (1995) includes a compliment of 5,000 photon torpedoes and in Star Trek: Nemesis (2002) the Enterprise-E is shown firing both photon and quantum torpedoes. Quantum torpedoes may be more powerful, especially against shields, but they are not as accurate and don't have an adjustable yield like photon torpedoes, making them practical in only certain situations.
This is not correct, the Defiant was the first starship equipped with quantum torpedoes, at this point they are still considered experimental and the Defiant is the only ship in the fleet with them, but she is also equipped with photon torpedoes. Sovereign-class starships like the Enterprise-E are the next class equipped with quantum torpedoes, but she also carries photon torpedoes, at this point most ships in the fleet are equipped with just photon torpedoes. For example during the opening battle with the Borg cube in Star Trek: First Contact (1996) (which is over a year after this) there are several ships seen firing photon torpedoes, the upgrades DS9 receives in The Way of the Warrior (1995) includes a compliment of 5,000 photon torpedoes and in Star Trek: Nemesis (2002) the Enterprise-E is shown firing both photon and quantum torpedoes. Quantum torpedoes may be more powerful, especially against shields, but they are not as accurate and don't have an adjustable yield like photon torpedoes, making them practical in only certain situations.
14:45 during the scene on the bridge, a boom mic and even the boom on which it is mounted is clearly visible at the top edge of the screen centered approximately over the captains chair and remains visible (and moving) from that camera angle.