It's an extremely colorful set as these images from www.mycomicshop.com show:
You can see the plastic clip may have come attached already to the body of the plane. Spiderman and Iron Man were one of five main, recurring characters on the cartoon. The Incredible Hulk, Thor and the Prince Namor the Sub Mariner were the others. I suppose Namor was added to provide a little variety, allowing the use of underwater adventures as the other superhreoes were air and land based essentially.
The wrapper shows the Human Torch:
As we'll see on the back though, not all of the Fantastic Four made it to styrofoam:
No Mr. Fantastic or Invisible Girl? Yikes! And Dr. Doom even made the cut:
I'll leave you with this gallery shot; it shows all the plane bodies and as you can see, some were not really main characters:
You'll be forgiven if you don't recall The Angel or The Wasp. And the spelled Daredevil wrong!
Still, it's a very nice set commemorating a very bad cartoon. Even as a kid I could tell it was cheaply made. Give my Bugs Bunny any day!