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.
Suggested correction: Dr. Weir doesn't crush DJ's throat at all. The noises he makes are simply choking noises because he is being picked up by his throat, there isn't even anything in the scene to imply his throat is being crushed, which in reality requires considerably more effort than most people believe.
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.
Continuity mistake: 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.
Revealing mistake: 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 mistake: 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.
Suggested correction: The blood was real. That's why you see it on her face. It wasn't an illusion and the blood isn't gone, it just drained away through the grating.
Factual error: When the gravity drive is activated not only does she say 'Gravity in five' and it turns on instantly but when the liquid coolant begins to fall, it falls from bottom to top, like the bubbles are draining out of a container, the tops of them stay intact until they are the last parts to drain, gravity however would affect the whole mass all at once making the balls simply fall as a distorted whole and splash into the floor.
Continuity mistake: Just after Dr. Weir's encounter in the circuitry tunnel, an exterior "fly by" shot shows the Lewis and Clark docked on the Starboard side of the Event Horizon. All other exterior shots show her docked on the Port side (including the docking sequence scene).
Plot hole: The use of massive explosives to separate a ship makes no sense as the explosion would send fragments at high velocity in every direction guaranteeing it would penetrate whatever ship is remaining. As we see in the final scene when the ship does blow apart, it is not a precise controlled detonation to sever connections but a total (and glamorous) explosion which makes no sense whatsoever.
Suggested correction: The explosions breach the outer hull, pulling the debris outward with the explosive decompression, the film shows the ring shaped explosions at both ends of the corridor. The debris wouldn't hit the lifeboat because it is heading in a different direction.
Plot hole: An engineer on a rescue ship seems to be the first person instead of the entire planetary intelligence community and the NSA (as reported by Dr. Wier) to translate basic Latin from what the Event Horizon's captain said. Somehow nobody else with all the vast resources of the NSA and other government organizations could clean up the transmission to determine exactly what was said?
Revealing mistake: During the opening scene, when the camera is starting to zoom in on the ship outside earth's atmosphere - the view of the crew inside zooms in quicker than the camera moving in to zoom into the cockpit.
