The first Sonic the Hedgehog movie trailer pretty much lead to an internet meltdown, and not in a good way. People were horrifed by the design that was being used, and the backlash was loud and swift. Surprisingly, Paramount actually listened and pushed the film back to rework Sonic's design.
The film is now due out Valentine's Day, and the redesign of Sonic has gone over extremely well. Of course, all that comes at a cost. While the animators involved certainly have to work overtime, we're hearing that Paramount actually spent another $35 million getting things together. That pushed the budget for the movie from 90 million to 125 million.
UPDATE - We have a second report on the redesign, which gives a different figure. According to a source close to the product says that the character redesign cost Paramount less than $5 million. This was because most of the film's VFX work wasn't done, and what was seen in the trailer was among the few 'final' scenes that were done. With that said, there's still a lot of marketing costs involved with the redesign as well, which could account for the rest of the money quoted in the original report. Thanks to OperationGamer17 for the heads up!