Ramis pinpoints the film as something of a turning point for Murray as a screen presence, telling Time Magazine, "In that role he actually got at the edge between the better, higher, gentler Bill and the bad, cranky, dark Bill. He figured out how to project the entirety of himself through character. When we were making the film, I'd launch into some explanation of the scene we were about to do, and he'd say, 'Just tell me - good Phil or bad Phil?'" Some other interesting casting notes: a British music magazine at the time pictured singer-songwriter Tori Amos with a copy of the script. It turns out she was being considered for Rita, the role eventually played by Andie MacDowell. Also, keep an eye out for the first screen appearance from Michael Shannon, who plays Fred, the young soon-to-be-married man whose bride, Debbie, is having second thoughts.
Screenwriter Danny Rubin spent much of his twenties in Chicago, trying his hand at various creative pursuits, before settling on screenwriting. He'd sold one script already when, inspired by Anne Rice's "Interview With The Vampire," Nietzsche's "The Gay Science" and William Dean Howell's "Christmas Every Day," came up with the idea of a man forced to live the worst day of his life over and over again. Once he had that germ, Rubin related "the first thing I thought of is, I’ve got to think of which day he repeats. Which day is it? And so, I just opened up the calendar and the first holiday day I came to was two days later, Groundhog Day, and I was thinking about that saying, 'Well, this is perfect. It’s a completely unexploited holiday. We can play it on TV every year like the Charlie Brown specials.' But, other things started to make sense immediately too, like I wanted him to be a character who went somewhere and was in unfamiliar territory. If he was on his home turf with his family and friends, it would be a completely different story." The script took about seven weeks of outlining, but was then written in an alarmingly fast three or four days. While studios originally passed on it, despite universally loving it, CAA managed to get it to Harold Ramis, who jumped right aboard.
But the script was in quite a different form back then. For one, it began in media res, as it were. Rubin explains. "The first things that happens is you hear the clock radio come on with the 'I Got You Babe' and then the DJs come on doing their little shtick and Phil is able to sort of mouth the words to what they're saying when he wakes up before he even knows what they're saying and the audience is thinking, 'Huh, that’s strange. How does he know what's playing on the radio?' And then he goes downstairs and he knows what Mr. Lancaster is going to say before she says it, so he’s anticipating and the audience is thinking, 'Wow, this is weird. How does this guy know what’s going to happen before it happens?' Then he goes outside and this geeky goes, 'Phil?' and Phil goes up to him and takes off his glove and he slugs him and we have no idea why that happened. And so, I set it up by beginning in the middle with this mystery. How does this guy have this supernatural ability and we go through meeting, you know, going through the Groundhog report and setting up the day and then he repeats the day and that’s when we know how the movie is set up and we understand how he knows what he knows..."
Rightly, Ramis suggested that the script should set Phil's normal life up first as well as cutting the original ending, which, as he told the New Yorker, saw Rita "reveal that she’s trapped in her own endless repetition, and that there’s no existential relief in sight." The studio also tried to get the writer to add a scene that explained Phil's predicament as the result of a gypsy curse put on him by an ex-lover, but Ramis refused to shoot it. One thing that Rubin was insistent on, as he told The Guardian recently, was scrubbing the script of any 1990s pop culture references, lending it the timeless quality that means it holds up as well today as it ever has.