Other mistake: When Seven talks to Lt. Com. Tuvok when he is shaving, she refers to him as "Lieutenant," rather than "Commander." Starfleet follows American naval doctrine with respect to rank structure and military courtesy - Lieutenant is not an acceptable abbreviation of Lieutenant Commander, and with the Borg having assimilated Starfleet vessels and individuals in the past, she'd know their rank structures.
Mortal Coil - S4-E12
Continuity mistake: The shuttle is "parked" in the nebula to get a protomatter sample, and the nebula is visible in all windows. After the shuttle is hit, the camera looks at Tom, and the view in the window is the black of space with stars, rather than the bright nebula.
Other mistake: In this episode Voyager sends the doctor to a federation ship in the alpha quadrant through a transmission using an alien communication network. Right before he is sent you see him in the astrometrics lab and he steps up on a platform wearing his mobile emitter. His program is then sent through the data stream and the mobile emitter is sent with him. Then when he arrives it is not there. Firstly, the mobile emitter can't be sent this way, only the doctor's program can. It can be beamed but that was not the case here. Secondly, in other episodes where the doctor is taken offline while wearing the emitter they show it drop to the ground. They don't do that here as it appears to dematerialize with him. (00:07:00 - 00:08:00)
Continuity mistake: The array surrounding the micro-singularity is shown collapsing twice, once when weapons fire causes Voyager to lose control over the anti-thoron radiation it is emitting and again when Voyager is attempting to beam Seven of Nine and Tuvok off the Hirogen ship.
Character mistake: Species 8472 was trapped on deck 11, behind a force field. When the ship comes under attack by Hirogen, Seven is instructed to get down to deck 11 with a supply of nanoprobes. In the meantime the Hirogen hunter escapes from Sickbay (deck 5) and soon faces off Seven and attacks 8472. When Seven beams them off the ship, Harry says that 'someone has tapped into transporter control on deck 5'. (00:39:00)
Continuity mistake: When Seven gives her log entry at the beginning of the episode, she lists the Star Date as 15781.2. This is a misstatement of the correct star date, 51781.2.
Continuity mistake: Early in the episode, the Kyrian historical researcher plays a simulation of events aboard Voyager that include Janeway killing a Kyrian and then throwing the rifle to a crewman. Later, he replays the simulation for the Doctor, but subtle details of this 'same simulation' change, most notably the way the female crewman raises her rifle much sooner the first time we see Janeway walk past her, and the difference in the way the male crewman catches Janeway's rifle. (00:14:15 - 00:26:20)
Plot hole: The atmosphere of the Class Y "Demon" planet is repeatedly said to be highly corrosive and unable to support life. It isn't even safe for Voyager to stay in orbit for very long and Paris and Kim's spacesuits begin to fail after a while of being on planet. However, their shuttle, having been landed on the planet for several hours by the time Chakotay and Seven find it, shows no sign of damage. Even the leather upholstery of the seats or carpet interior (the rear hatch having been left open) isn't dirty. If Starfleet has built its starships and spacesuits out of that same upholstery, this mission would have been no problem.
Deliberate mistake: When the Doctor begins to "fade" in the transporter room his mobile emitter fades with him. Since it's made of solid matter and is not a hologram, this shouldn't be possible.
Continuity mistake: In the scene where Tuvok is performing the meld Seven of Nine's hair is noticeably out of place as a result of struggling in the restraints, yet just after the Vinculum is deactivated it is neatly back in place. (00:38:15 - 00:42:50)
Continuity mistake: When Seven and Naomi are playing Kadis-Kot, the pieces on the board and on the table change after Seven wins in the next shot.
Revealing mistake: As the camera looks into the Jeffries tube, it's easy to tell that the view beyond the second bulkhead is a matte painting used to extend the set.
Character mistake: Captain Janeway's main goal in this episode is to proceed to the holodeck and shut down the lightning shield protecting Chaotica's death ray so Lt. Paris can shoot it with his destructo beam. Throughout the scene where Lt. Paris further briefs Capt. Janeway on her way to the holodeck, the plot is such that her goal is to shut down the death ray, not the lightning shield. (00:26:20)
Suggested correction: They are trying to shut down everything in the Holodeck simulation.
Continuity mistake: When Tuvok and Paris go scouting the holodeck, Chaotica's fortress is visibly damaged, but in a later shot when Kim and Seven are looking at it from astrometrics, the building looks like it's completely intact.
Character mistake: Captain Janeway states the temporal differential ratio is .4744 seconds per minute (meaning for every minute on the surface, only .4744 seconds pass on Voyager). Tuvok calculates that 30 minutes on Voyager would be 2 days 11 hours and 47 seconds. However, at that ratio, 30 minutes would be 2 days 15 hours 14 minutes and 15.9 seconds. Later Tom (who was on the surface) says the last two months for them was only 2 days for B'Elanna (who was on Voyager). But with the temporal differential, 2 months on the surface would be less than 12 hours on Voyager. 2 days on Voyager would be almost 253 days (almost 8.5 months) on the surface.
Character mistake: Neelix says that the Great Wall of China, prior to the 22nd century, was the only man-made object visible to the naked eye from orbit. This statement has been long-since debunked, but it's not unreasonable to think the myth perpetuated itself in the future. Still wrong though.
Continuity mistake: Paris reports that several ships have dropped out of warp off of Voyager's port bow, but when the ships are put on screen, they are approaching from starboard aft.
Visible crew/equipment: When the former Borg drones are awakened in sickbay, there's a pinkish T-mark visible on the floor behind Seven, at the bottom left corner of the screen. (00:19:10)
Continuity mistake: When Tom explains to Alice why he can't leave the Voyager, he has a three-day beard. Later in the ship, when Alice convinces him to turn on the neurological interface, he is cleanly shaved. But in the next scene he has his beard back again.
Revealing mistake: As Seven starts to explore, there's a flashlight floating next to her. There's no atmosphere, therefore no breeze, but it's slightly moving before she touches it.