"X-Men: Days of Future Past" has been tagged as the second most expensive movie that Fox has ever made.

The numbers are estimates and no official number has been quoted but with the cast alone, it is definitely a contender.

Bryan Singer himself admitted that on IGN when he confirmed the title:

"It's going to be very ambitious. It's called Days of Future Past and it deals with aspects of that comic but also, some very new things."

The 'very ambitious' took on a financial aspect. Bryan Singer must have a lot of sway with Fox to convince them to greenlight this scale of a project. While the principal shoot has finished, there have been confirmed reports that there will be reshoots in Montreal. It has not been revealed which cast members will be involved.

The movie will span two sets of X-Men teams from two different eras. They cast the new set of actors from "First Class" like James McAvoy, Michael Fassbender (both if whom became A-listers since the first movie) and Jennifer Lawrence who is now an Academy Award winner. The original X-Men cast will also appear, particularly Hugh Jackman, Halle Berry and the older versions of Professor X and Magneto, Patrick Stewart and Ian McKellen. Also reprising their roles are Ellen Page and Anna Paquin.

New additions like Peter Dinklage (Game Of Thrones), Fan Bingbing, Omar Sy and Booboo Stewart also drive up the expenses. If you add in the Sentinel robots, that could easily exceed the $ 200million mark.

Now the pressure is much stronger for the movie to deliver. The movies that cost this much made more than a billion dollars worldwide. Even Grand Theft Auto V which cost that much made a billion.

The formula of cramming in a lot of mutants onscreen is a tactic that will arouse the viewer's curiostiy. However, it may backfire when they fail to make a cohesive and seamless connection between the timelines. It may become the most epic superhero movie or a grossly expensive Halloween party.