RE: Big Cast Movies
I've only heard of this one: "The Phynx" from 1970, it's a pop-band/secret agent comedy that sounds like it's got a 'Monkees' vibe to it. The 'stars' were unknowns then and still are, but these are the folks I do recognize:
Joan Blondell, Martha Raye, Pat McCormick, Rich Little, Busby Berkeley, Xavier Cugat, Ruby Keeler, Joe Louis, Marilyn Maxwell, Maureen O’Sullivan, Harold 'Oddjob' Sakata, Ed Sullivan, Rona Barrett, James Brown, Leo Gorcey, Guy Lombardo, Butterfly McQueen, Richard Pryor, Harland Sanders, Rudy Vallee, Johnny Weissmuller, Edgar Bergen, Dick Clark, Andy Devine, Huntz Hall, George Jessel, Dorothy Lamour, Trini López, Pat O’Brien, Jay Silverheels, Clint Walker, and Sally Struthers.
If this movie surfaces anywhere I'll have to see it, if only from curiosity.