Well, I cracked a significant part of the mechanics for collapsing bridges.

The controller object is the most important. It has an X and a Y, which it checks against Trevor's, just like every other non-Belmont in the game. When Trevor is to the right of it at least #$40 pixels away, it goes into Collapse Mode.

First, it looks for the lowest free RAM offset and then duplicates itself, applying a sprite to the child (since the controller itself has no sprite). It then scoots itself over $10 pixels and triplicates. Then it scoots over again and quadruplicates. And so on and so forth. It does so for 20 or so blocks. Each child block is comprised of a complex animated sprite.