There are plenty of funny bits throughout the film with spoofs of Steve McQueen's Bullitt detective, to Margaret Hamilton from The Wizard of Oz in some sort of oddball part singing the "Star Spangled Banner" Altman also has lots of throwaway jokes scattered all over the film which were probably improvised during the shooting
What does it add up to? I don't think even Altman ever knew. After throwing in lots of little jokes about birds, high speed car chases and oddball character touches, he starts killing off his actors with some sort of "Angel of Death" played by Sally Kellerman.
In the end I suspect Brewster McCloud was Altman's way of seeing how much he could get away with in a studio financed film. Robert Altman made so much money with MASH for 20th Century Fox, MGM probably thought he could work a similar money making miracle for them with his hipster sensibility. They were in for a big surprise.
105 minutes, written by Doran William Cannon.