Continuity: Deanna is originally sitting on the bridge when they approach the zone of darkness, but after Picard tells Wesley to take them in, in the next wide shot Deanna disappears entirely and doesn't reappear throughout the rest of the scene - she only reappears much later when Riker and Worf return.

Continuity: Klingons measure distance in kilometers in this episode. However, in all other Trek shows and movies, they measure in kellicams. [This was apparently during a misguided attempt by the Empire to adopt the decimal system (for Galactic consistency), even though the change was wildy unpopular with the public and military alike. While some ships, like in this episode, gave it a good try, the change was short-lived and eventually abandoned. However, until this claim can be backed up by a reference within Star Trek canon, it stands as a mistake.]

Other: After viewing the clash between the governess and her protector, the camera shows Wesley. His communicator badge is completely silver, instead of the standard gold and silver.

Revealing: When Geordi closes the 'dead' Data's eyes, it is obvious that he just passes his hand above Data's face, without touching his eyelids.

Factual error: 30 seconds in Geordi says: 'surface temperature -291 degrees Celsius'. (The scale only goes down to -273.15 which is absolute zero).

Visible crew/equipment: In the observation lounge, you can see a shadow from a crew person on armrest of the chair on the bottom left of the screen. Hard to see, but definitely there.

Continuity: Worf says the Borg have locked on a tractor beam, but in the next exterior shot there is no tractor beam visible between the two ships. Later there is.

Audio problem: In Engineering when Worf says "Ensign.", Michael Dorn's lips don't move.

Continuity: Wesley says that he's departing shuttle bay 2, but on the floor, it says shuttle bay 3.

Continuity: When the head Bringoidy starts a fire in the hold, Worf informs him that a force field will cover the fire until it is extinguished. But in many later episodes you see fires burning, and nothing happens. At most, they will let the air out of the room, but no force fields.

Continuity: The Bringloidi leader keeps saying that they've spent 300 years building their society, but this episode takes place in 2365, and it's stated that his ship launched in 2123, making it 200 years.

Continuity: In the beginning of the episode, Riker, Geordi, Worf, Data, and Pulaski are playing poker. Pulaski puts two neat stacks of chips in the center beside some chips in a pile. It then shows Worf putting similar stacks in the center but Pulaski's stacks are not visible and they should be. Then when Worf wins the hand, the camera is showing a wide shot of him pulling the chips towards him and you can see his and Pulaski's neat stacks of chips.