Advertising Action Hour: The Crossover That Wasn't

Going through the old comics for my Back Issue Alphabet articles, I occasionally run across some fascinating old adverts. Mostly they serve as time capsules, either promoting soon-to-fail game systems or movies that have faded into obscurity, but sometimes I find some that blow my mind. Like this gem:

At first glance I thought it involved some sort of company crossover series involving Spider-Man, Robocop, and the Dino Riders all appearing in one very special episode, a la Cartoon All Stars to the Rescue. Unfortunately, a quick Wikipedia search reveals that it was mere a block of programming involving all three cartoons. Ah, nuts. 

And then there was that advertisement that featured Magneto, Dr Doom and Elton John going Christmas caroling:

Wait, what?