What is the sleigh crash of 1964?

They are referring to the difference of how Santa and his elves look between the 1964 Christmas Special Rudolph the Red-Nosed Reindeer and 1974's The Year without a Santa Claus. I am going to use a Star Wars reference when Mark Harmill who played Luke Skywalker got in a car crash that scared his face they explained this by using a Wampa attack in the movie. With Santa's sleigh crash of 64; they explain the new look of Santa with a sleigh crash with a Russian satellite.