I thought of my cast for all of 5 seconds, so the list's a bit half assed.
Max- Michelle Rodriguez

Because her face is somewhat similar to Jessica, and she's also a tomboy, like Max.
Logan- Sean Bean

Looks a bit similar to Michael Weatherly. His accent would be a bit of a problem, but I bet he could learn.
White- ?
Lydecker- Dennis Hopper

Dunno, I just think that he could make a good Lydecker.
Sandeman- Sean Connery/Morgan Freeman
A wise old scientist with a stick it to the man attitude? Is anyone else even remotely suitable?
Do you know an actor that could replace someone from the current cast, and maybe even suite the role better than one of the current actors, then post it here.