REED RICHARDS IS A SCIENTIFIC PRODIGY WHO HAS BEEN QUIETLY EXPLORING THE UNIVERSE’S DEEPEST MYSTERIES IN HIS GARAGE, AFTER SCHOOL. AFTER BEING TRANSFORMED BY ONE OF HIS EXPERIMENTS, HE CAN WARP THE SPACE AROUND HIM, AND APPEAR TO STRETCH HIS BODY INTO IMPOSSIBLE FORMS AND TO INCREDIBLE LENGTHS.
It was all just a clever way of trying to explain Mister Fantastic's (Miles Teller) powers that was a little too complicated.
Speaking to HitFix, Fantastic Four screenwriter Simon Kinberg set the record straight. "I think it was confusing. I was a little confused by it myself. The intent was to try to explain the power with some sort of scientific explanation, but as you pointed out, most of his powers defy what we know about physics. The upshot of it is that he stretches in his movie. That is his power. That's the simplest explanation."
As far as the J.J. Abrams-type of secrecy surrounding the project is concerned, Kinberg stated it's really just a byproduct of trying to make sure things are perfect, visually, before they're released. "This thing here, it really has been a concerted thing because we really just don't want to show anything until it's ready, until it looks great, and they show the real intention of the shot or the movie, then we'll show it. That's why we've held on to so much. We held on to the Thing. We held on to Doom. We held on until we were further along."
In reality, it should have been obvious that Reed will stretch in the film. Hell, there was a stretching scene in the most recent trailer. However, "the internet" turned a blind-eye to this fact and simply wanted to cause a bit of controversy. Kinberg also points out that as the promotions for the film ramp up, information and marketing assetts will be released from many different sources that's nearly impossible to keep under the supervision of a single voice.