I have not seen the movie or read the book.  But reading Kevin Mac
Donnell's comments and Hal Bush's thoughts on it brings back a vivid
chapter from Robert Caro's _The Years of Lyndon Johnson: Master of the
Senate_, p. 888-89 in a chapter titled "The 'Working Up'".  LBJ discusses a
conversation with Gene Williams, his maid's husband, about Williams's
reluctance to drive LBJ's car along with LBJ's beagle from Washington, DC
back to Texas during the Senate recess. He quotes Williams, "a colored
man's got enough trouble getting across the South on his own, without
having a dog along." LBJ told several versions of such a incidents
including another about his cook, a college graduate and her husband who
drove the limousine of the Vice President of the United States back to
Texas. "When they had to go to the bathroom, they would stop, pull off on a
side road, and Zephyr Wright, the cook of the Vice President of the United
States, would squat in the road to pee. ... That's wrong." The chapter is
available on google books and the amazon search inside feature.

Barb