Mant is one of the finest movies never made. It's actually the fake movie which is central to the plot of Joe Dante's early 90's nostalgic opus Matinee which takes a gander at what life might have been like in the Florida Keys during the Cuban Missile Crisis.
Matinee has a wit and charm which surmounts its nostaligic sentimentality. John Goodman portrays a vintage huckster slash showman named Lawrence Woolsey who is in the trenches of old time movie making and attempting to make it big with monster and horror flicks geared toward the mass audience. He is a spin on the real world William Castle and it's difficult to say that Goodman's portrayal is broader than reality since Castle was such a large personality, but it's fair to say that Dante's affection for the work of Castle limits the defects we are treated to in Woolsey. He's a generous, big-hearted larger than life man who brings gusto to even the tiniest aspects of his life. And in the movie we meet a young man who finds in Woolsey a father figure who fills in while his real Dad is off defending the United States from the encroaching nuclear missiles just to the South.
The movie-in-a-movie Mant is a send up of the vintage sci-fi flicks from Universal and other studios which dominated the early years of the Cold War and in many respects reflected much of the anxiety of that era. Even the "M" from Mant on the marquee (not on poster though) is the "M" from The Deadly Mantis one of the more brisk of the giant monster flicks and one which drew direct parallels to the nuclear threat from above. The monsters in those movies were big and scary but they were never as scary as real life had become in the last half of the 20th century. Monster movies could only ape and imitate the dread which dominated the culture in many ways and which still does really.