Following the success of Deadpool's R-rated release, some film fans have been clamouring for other similarly rated comic book films. Batman v Superman's theatrical release won't push things quite that far, but its release on DVD and Blu-ray down the road apparently will.
A recent bulletin post by the Classification and Rating Administration (CARA), which was discovered by pop culture website Epicstream, indicates that an R-rated 'Ultimate Edition' of Batman v Superman: Dawn of Justice has been classified for US audiences. This rating was slapped on because of "sequences of violence."
It's specifically mentioned that this is an "edited version" of the film and states that its content "is different from PG-13 version."
The Ultimate Edition is yet to be rated in other territories, but it's likely (and possibly hoped) that this edition will be submitted elsewhere at a later date.