There's a very funny scene in the first season of the Walton where John Ritter stars as a young preacher. He visits the Baldwin sisters and has some of their alcoholic "recipe." He shows up at the church and starts to get out of the passenger side of the truck. He is very drunk. He say, "Friends and neighbors, thank you for..." - then he twists and falls out of the truck and flat onto his back on the ground, all in one take. An impressive stunt.

It was supposed to be a serious scene but anything physical stunt he did was flat out hilarious.

There's another scene in season 2's "Thanksgiving Story" where John Boy gets a blood clot in his brain after a lumbermill injury. He visits the reverend (John Ritter) and is walking back to his truck when he has a spell and falls onto the ground.

It's not a funny scene, and it's not as dramatic as a John Ritter fall, but I have no doubt that Ritter probably coached Richard Thomas or even suggested the stunt to the director.