...Wouldn't that mean that every other actor in every other scene with Leary (with the exception of the "Mickey Mantle" speech) have to improvise as well?
This seems - to me, anyway - entirely unlikely.
Tim
Yes, by default, that would mean that all lines delivered in response to Leary would have to be improv'd, to some degree or another. It's not as unlikely as you might think. Leary made up most of his dialog on the spot, and I know that Walken did some ad-libbing as well. I've heard Jay Mohr talk a little bit about the production in his stand-up routines, and it sounded like the actors were welcome to contribute any ideas that they might have had. Lots of actors, especially those who work mainly in film, don't just do the same thing over and over. They'll vary lines and movement from take to take, be it out of boredom, a desire to keep the scene fresh, or just to give the director more options.
If you're working in Shakespeare, this approach won't get you anywhere. On a David Mamet production, it'll probably get you fired. Some guys, you just don't rewrite. On the other end of the spectrum, you have Christopher Guest's movies, Ghostbusters, or really anything that Bill Murray's ever appeared in.
Yes, and they did. Remember there were multiple takes that allowed these things to develop as well.
If you listen to the commentary, most of the actors improvised heavily. All or most of the comedic dialogue was added by the actors during shooting.
"It's that kind of idiocy that I empathize with." ~David Bowie