Reed, Sue, Ben, and Johnny aren't the only ones going through some changes. From the first trailer to the last and latest, it appears that Josh Trank and the folks behind Fantastic Four decided the movie needed to be a little more green.
No, we don't mean they decreased the movie's carbon footprint - they literally changed colors from red to green. When the team goes to the alternate dimension that gives them their powers (which, whether it's called it explicitly or not, is most likely based on the comics' Negative Zone), the energy coursing through the planet was red in the first trailer, and is now green. It was first spotted by fans on Imgur and Reddit.
So why the change? Well, as one fan points out, the red looks a lot like lava, and it doesn't seem (from the new version, especially), that was the intended look. That distraction alone is likely a good enough reason to change things up.
While the Negative Zone in the pages of Marvel Comics doesn't have any kind of standardized color scheme, green certainly has been present. Even on the animated series Hulk: Agents of S.M.A.S.H., when they went to the Negative Zone and fought Annihilus, green was the prevailing background color. Green, of course, winds up also being the color people most associate with Doctor Doom, the film's villain, due to his colored outfit.
This is the hard part about making movies with a lot of special effects, throwing trailers out during the editing process instead of after it; movie choices may not be finished just yet, and things change.
Fantastic Four stars Miles Teller, Michael B. Jordan, Kate Mara, Jamie Bell, and Toby Kebbell, and is directed by Josh Trank. Fantastic Four is scheduled to be released in movie theaters on August 7, 2015.