Deliberate "mistake": Strange how the crew of the Lewis and Clark don't stop and take a good look at the planet Neptune, even for a little bit, let alone comment on it.

Factual error: When D.J. is attacked by Dr. Weir, he is grabbed by the throat and is squeezed until his windpipe is broken, shown by the way he was breathing (or struggling to). When Weir seizes him again and throws him against a support beam, he screams in a way impossible for someone who just had his windpipe crushed.

Revealing: In the scene where Sam Neill has set the bomb to blow up the rescue ship, Laurence Fishburne comes running up to the sealed door of the Event Horizon whereupon it shakes back and forth like a stage door would.

Continuity: When the crew go to sleep in the water-filled gravity tanks, they all wear masks for oxygen intake. Yet, when Dr. Weir, at the film's beginning, and Lt. Starck, at the film's end, are ejected from the tanks, they are not wearing oxygen masks.

Plot hole: In the scene where Lewis and Clark nearly hit the Event Horizon, One of the crew is calling out the closing distance and another confirms this information. Regardless of clouds obscuring their view they were aware of their proximity and the fact that they were speeding towards it and forced to attempt an abrupt stop makes no sense.

Plot hole: After Smith and Peters gather the remaining oxygen tanks and head for the Lewis and Clark, Peters, distracted, stays behind, and is killed. She is discovered by Dr Weir. Thing is, Smith had a head start; he should have encountered Weir and demanded that he head to the Lewis and Clark too. And why is it that Smith never noticed that Peters had disappeared from behind him?

Continuity: Throughout the entire movie the size of the Event Horizon's interior versus that of its exterior is repeatedly off. Evidence of this is seen mostly with scenes that take place in the main access corridor. First off, it is made to seem that the ship has one central connecting tube, but in the exterior shots there are several tubes that make up the middle of the ship. This is pointed out when Miller is making his way across the ship to get to the air lock that Justin is about to open. Second, the length of the tube (heck even the whole ship) is too small in relation to how the ship appears from the outside. This is pointed out in a few different places in the movie - when the crew is up on bridge, then race all the way to the airlock in the middle of the main access corridor, where Justin has just closed the inner door and when the doctor is asked to go grab his med kit from medical, which is across the ship and he is gone only a few seconds, and also when Miller is running though the corridor to activate the explosive charges. Since the ship has no faster means of transportation, such as turbolifts or a tram system, they could not be covering the distance they appear to be covering in the movie.

Continuity: In the last few scenes where Lt. Starck is getting ready to prep the Gravity Pouches, the tube in front of her fills with a bloody substance, then shatters, sweeping her away. She then falls down a hole in the floor where the ladder is. Later, when the tube is whole and the blood gone (showing that it was a last ditch scare attempt from the ship) she still has blood on her face. It couldn't be from the fall, either, because she landed on her back and wouldn't be bleeding from her hair line.