Even the crack team of JJ Abrams and Steven Spielberg, working with a $50 million budget, still had a few anachronisms in their film, Super 8, set in 1979. A few examples:
First - in the convenience store, Breen shows off his Walkman in June, 1979.
Per Wiki:
"The metal-cased blue-and-silver Walkman TPS-L2, the world's first low-cost portable stereo, went on sale in Japan on July 1, 1979. "
http://en.wikipedia.org/wiki/Walkman
Secondly, regarding the building blocks of the alien's ship - one of the kids says they look like silver Rubik's cubes.
From wiki:
"the puzzle was licensed by Rubik to be sold by Ideal Toy Corp. in 1980"
http://en.wikipedia.org/wiki/R...27s_Cube
Of course, if there were Super 8 apologists, we'd be getting all kinds of convoluted theories on how it might be possible that the clerk got an advanced demo model of the Walkman, or maybe one of the kids' fathers worked for Rubik on R&D.