Question: Why did the Event Horizon choose to come back after seven years? In fact, why come back at all?
Question: What exactly happened to the original crew of the Event Horizon? Where did they go after they tortured each other?
Chosen answer: At least one crewmember is seen as a floating, frozen corpse on the bridge of the ship when the rescue crew are exploring, there is also evidence seen that a significant amount of tissue and blood have been spread around the walls in some parts of the ship, however it is implied that the original crew are in the alternate Hell dimention, if not physically then spiritually.
Question: 1) In the big finale where the gateway was opened: was the ship destroyed before it went through the wormhole or did it blow up as it was going through - trapping everyone in Hell? 2) In the final scene just before the gateway is opened, there is an argument going about whether Miller's crew are alive or dead and talk about them belonging to the ship. We saw the crew die, so I fail to understand the mental imagery of their suffering Miller was shown. Also, if the crew belong to the ship to replace her old crew - why haven't we seen anything of the old crew?
Answer: As a representative of Hell, Dr. Weir was torturing Captain Miller with all sorts of horrific mental images. Miller cared very much for his crew, so Weir fabricated hellish visions of his crew. And the aft section of the ship didn't blow up, it was sucked into the Hell dimension.
Answer: The only ones who were sucked into Hell were Captain Miller, and Peters...as her body was in the same core room with Miller and Dr Weir. When Miller detonated the explosives he separated the rest of the ship, leaving only the stern to be sucked into Hell. It's a very sad and dark ending.
Justin ("Baby Bear") was the first crewman visibly sucked into the Hell dimension, which pretty much destroyed his mind.
Chosen answer: The movie never explicitly says; but science is as yet unsure what happens to a given piece of matter once it crosses a black hole's event horizon, so who knows? The ship could have been thrown seven years forward in time, or far enough away that it took seven years for it to drift close to Neptune. Pick any explanation you like.