Casting Squires

I love Kingsley's performance, but I'm wondering if Elias Koteas could have done the role. My first idea was that they made Ben try to sound like Robin Williams's normal speaking voice, but some of the scenes where he's even more than that sound and seem pretty much like Koteas naturally. I've seen him in a flat cap so I'm pretty sure he could pull off the look shown on the poster.

Oh and I just found out there's a Dr. Jeffrey Squires MD in Minnesota!