Question: Near the beginning, when Alfred sees Bruce is not in bed, he goes to the Wayne Enterprises private property. There a weirdly shaped metal structure that looks like it's tilting over and what looks like a dilapidated building in the middle tilted to the side. What is the structure supposed to be?
Answer: It looks like a large panel on the side of the huge crane. I think it has openings for access to the crane machinery or something like that. Maybe a crane operator could describe it better but that's what it looks like to me.
Question: Did Heath Ledger manage to film all of the scenes he was supposed to before his death?
Answer: Yes he did. I think principal filming was finished in November of 2007. However, it should be noted he did not finish filming all his scenes for "The Imaginarium of Doctor Parnassus" (2009).
Answer: Yes, he died a few months after principal photography ended.
Question: Did Harvey Dent know that Bruce Wayne was actually Batman? His quote "Rachel's told me everything about you", and him telling Rachel that they were coming for her seems to imply this to me.
Answer: No, he doesn't know. His comment to Bruce is a very common expression, and it makes sense that Rachel would have told Harvey all about her childhood friendship with Bruce. Bruce's response, 'I certainly hope not', is a reference to his being Batman and he and Rachel's romantic history, both of which he would rather Rachel not broadcast. Harvey telling Rachel that they will rescue her is just to try and keep her calm while they try to figure out how to escape.
Answer: Additionally, if Harvey knew that Bruce is Batman, he would have had even more of a vendetta against him once he became Two-Face, since Batman rescued Harvey earlier and not Rachel. He may have even revealed Batman's secret identity to Commissioner Gordon at the film's climax.
On the other hand, knowing that Batman is Bruce Wayne could cause Dent to realise he is not the only one of who has lost something, Bruce did too. Batman would have a right to speak about whats fair.
Question: Why couldn't Batman just follow Lau to his house and kidnap him there instead of this elaborate plan with the plane?
Answer: To add to the other answer, Lau is likely to have heavy security no matter where he is, so an equally elaborate plan would be necessary even if he left his tower.
Answer: Lau probably lives and works at his tower.
Question: Why is the mob using that type of TV in order to do their video conference with Lau? Where is the camera?
Answer: It was a one way conversation. They could see Lau, but he couldn't see the mob. They had use retro television which is below the radar. They couldn't take the chance the Dark Knight had sophisticated equipment to trace the signal.
Not sure this answer is accurate. It is definitely a 2 way conversation, as Lau answers questions. Plus it looks like he is visually reacting to seeing the Joker walk in the room. None of which should be possible given that type of television that's being used, but that might be something for the mistakes section.
Question: How was Batman able to get to Harvey Dent faster than police to Rachel? I mean, I can think Bat's technology being way faster of course. But for example: if all units were sent to Rachel's location, there might have been some units patrolling near her location so it would have been faster to have them go there first. Right? What other possibilities am I not considering?
Answer: I honestly think within the context of the movie, we are just meant to assume that most units are either at the police station (given a high-profile terrorist suspect - the Joker - and many of his goons were just captured) or still at the scene of the massive chase that just occurred earlier in the night, since there was a lot of destruction or chaos. Thus, there simply wouldn't be any available units closer to Rachel's location. It's a little far-fetched, sure... but it's basic "suspension of disbelief." It's required dramatically for the plot to progress. (Similar to the fact that in the sequel, many of the Gotham City PD got stuck underground by Bane... it's a little far-fetched, but it works for the plot.) Batman was simply able to get to Dent's location faster since he's using the batpod, which is a bit of a technological marvel and can get around much quicker and easier than a police car.
Answer: This could be a plot hole, but I would posit: Given how corrupt/easily corruptible the Gotham police are, it's likely the Joker may have bribed/threatened/otherwise coerced the beat cops to a) steer clear of the areas where he was holding Dent and Rachel, or b) ignore the call to go to that location. You're right that Batman's tech is what allows him to reach Dent faster than Gordon et al. Reach Rachel; the Joker set it up that way, so that whoever Batman saves means the other one dies.
Answer: Batman showed up only a few seconds before the GPD, they arrived as the building blew.
Answer: We aren't shown exactly how the Joker pulls off any of his stunts, it's part of the mystery of his character. In order to pull off the two that you mentioned, the Joker would need meticulous planning and impeccable timing. It seems impossible to pull off either crime without anyone noticing but that's kind of the point. The Joker is apparently prepared for any contingency.
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