I remember watching the Bing Crosby film version one long Saturday afternoon as a kid. Lying on my front, chin propped on my hands, on the rug in front of the fire, wondering when Bob Hope was going to pop up and make the film funnier.
There's a scene near the start where he fools the populace into thinking he's a great magician because he happens to know there's an eclipse on the way. He tells them he'll destroy the sun unless they stop trying to kill him. That's all I remember from the film; it inspired me to look up the dates of all the eclipses in history, where they were visible, and how long they lasted. Just in case I accidentally time travelled. Better safe than dangling, twitching and drooling from the gallows. You'd feel such a fool if you hadn't prepared.
Bob Hope never turned up, as far as I recall. I also don't remember any tirades against the Catholic church or how monarchy was an evil institution designed to crush the little man, which is what most of the book is about. That could have whooshed right over my head, I was only seven or so.
I do remember another rainy Saturday when I watched "The Spaceman and King Arthur". This was Disney's version. It substituted an astronaut for the man who just bumped his head (much more plausible), going back in time after his futuristic McGuffin drive doesn't work. This guy was more of a dweeb than Bing Crosby or Mark Twain's original. In typical Disney fashion, dweeb has the right stuff in the end and saves the princess or something. He also has an exact replica of himself as a robot, for no other reason than it is useful for him later on when he has to joust against another knight. The knight beheads his robot, but the robot carries on fighting to gasps and swoons and general proclamations of great wizardry. No cries of "he's a witch, burn him!" since this was a Disney film.
Bob Hope never turned up to make this one funnier either, but this film made such an impression on me that I spent the rest of the day making a cardboard space shuttle, held together with lots of glue and a couple of paper clips, and a fully articulated cardboard robot.