"Mitt" is the work of Utah filmmaker Greg Whitely and will be released to the public next Friday through Netflix.
Whitely was given unprecedented access to Romney and his family as the former Massachusetts governor battled through the primaries to win the Republican nomination and then lost to President Barack Obama in November 2012.
NBC said Saturday one of the surprises in the film was Romney's sense of uncertainty on Election Night about the outcome of the voting. NBC said the candidate's feelings seemed to dispel the idea Romney was certain he would win and was stunned when Obama won a second term.
NBC said the film appeared to be carefully edited in deference to Romney rather than a truly independent chronicle of the campaign.