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.
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.
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).