Or just CGI. But as Cameron himself puts it (copied from the article linked in parent): > we could’ve run a CG helicopter under the freeway overpass, but it wa

Or just CGI. But as Cameron himself puts it (copied from the article linked in parent): > we could’ve run a CG helicopter under the freeway overpass, but it was so much more fun to do the real thing. I'm guessing the same applies from pulling a helicopter on a trailer. It's simply not fun.