Iron sky was created after someone played through all the wolfenstein games and then decided to play stellaris. This applies even more heavily to the second one.
Iron Sky is one of those movies that was great the first time I watched it, but when I watched it the second time knowing the plot and where all the jokes were going I realized it was actually pretty terrible (though still with a few funny moments here and there).
If you don't actually remember any of it, you might enjoy the rewatch.