The rumor of more explicit cuts first came about in an interview with the film's director, Chris Columbus, back in 2015. Columbus told Yahoo! that working with Williams was a gift because "the other actors had no idea what he was going to say." He then claimed that because of Williams's rapid-fire (and sometimes risqué) improvisation, there was "literally, a PG rated version of the film, PG-13, R, and NC-17.”
Now that the viral tweet has revived discussion around these potential versions, Columbus talked with Entertainment Weekly to clarify his previous statement. After confirming that there is actually no NC-17 version of the film, Columbus told EW that there are three different versions, including an R-rated cut. He said, "[Williams] would sometimes go into territory that wouldn't be appropriate for a PG-13 movie, but certainly appropriate and hilariously funny for an R-rated film. I only [previously] used the phrase NC-17 as a joke. There could be no NC-17 version of the movie."
When asked if the R-rated cut might ever get a release, Columbus said: "I would be open to maybe doing a documentary about the making of the film, and enabling people to see certain scenes re-edited in an R-rated version...The problem is, I don't recall most of it. I only know what's in the movie at this point because it's been a long time. But I do remember it was outrageously funny material."
However, Columbus added that he was pleased with the current version of the film saying, "I'm in a good place with Mrs. Doubtfire, so there's really no reason to do the definitive cut. The definitive cut of Mrs. Doubtfire is out in the world right now."