I'm trying to figure out where the notion that The Fantastic Four: First Steps is actually set in 1964 - as opposed to being set in the present with society on Earth-838 just having evolved with a retro-futuristic aesthetic ala the future world of Fallout - came from.
Might be a Sliders situation. They once slide to a world were I guess time moved slower so it was still the 1980's even though everywhere else it was 1995 or whatever year that episode was made. In that universe it might still be the 60's but as far as most of the multiverse goes it's all present day.
