Need help with prebricated Valve animations/scenes, etc

So today, confident in my utter lack of Source modding knowledge, tried to make a simple mod. In a nutshell, it's an Episode Two mod that contains the entire HL2 saga, from HL2 to the end of Episode Two (After fooling around with HL2 maps in Ep2 and seeing the graphical improvements, I wanted to see if I could do something like this).

Long story short, I got the mod launchable, the background bsps work, most titles work (except for the titles in the save window), all the buttons and icons are in their proper place and I'm sure they work, and progress through the first HL2 chapter works (Complains about old node graphs at each new loadpoint though).

Well, for the most part. Running along the rooftops, one of those squad cars drives into a lamp-post (node graphs fubar'd?). I don't recall seeing the Strider walk past. The biggest problem is the point at which Alyx saves your ass from a posse of Metrocops. When the world unglares from white, I'm looking at the floor, the same spot every time. Alyx talks, but I'm not looking at her, and she activates the elevator and gets in, but I'm stuck, looking at the floor. I'm guessing this is why (console error):

http://i26.tinypic.com/suygcx.jpg

So, what do I have to do to track down these animations or fix the problem?

If ye can deduce where the collision errors are coming from, that'd be helpful as well :).

Episode 2 doesn't have the script that scene needs, and HL2 and EP2 alyx use different collision models?

I've been looking for such a script in HL2's cache files, haven't really found anything. I suppose it could be hidden away somewhere else?

Edit: There's a series of tutorials, etc, that deal with mounting content, so in theory I could mount HL2 and Episode One onto Episode Two. Worth pursuing to see if it could help with my "missing anims/scripts" issue? (There's a Portal mod that loads HL2 and runs fine past the part I'm stuck at, so I'm wondering if it just mounted all of these things)