Anna Faris at the Los Angeles premiere of “Cloudy with a Chance of Meatballs” last year. (Photo: Mindy Roberts)

A production assistant rolls away the directors chairs Saturday at the Porter Square T stop in Cambridge after four hours of filming “What’s Your Number?” (Photo: Marc Levy)

Anna Faris, several dozen extras and the crew shooting the romantic comedy “What’s Your Number” spent some four hours in the Porter Square T stop Saturday — many commuters will probably say they know the feeling — for shots of Faris heading down to, and boarding, a train.

Production went afterward to a train yard in Southie for the next set of shots, an assistant director said. The cast and crew have been all over the map, shooting at Government Center as well as in the Boston University apartment area of the Fenway.

The movie bears the following not-too-inspiring synopsis on imdb.com:

A woman looks back at the past 20 men she’s had relationships with in her life and wonders if one of them might be her one true love.

And director Mark Mylod will also be an unknown to many, having done mainly television. (Some good television, though, including 23 episodes of “Entourage” and two last year of “United States of Tara.”)

The cast, though, is another, more encouraging, story: Zachary Quinto of “Star Trek,” Andy Samberg from “Saturday Night Live,” Joel McHale of the terrific sitcom “Community,” Boston-born Chris Evans, who will be starring in “Captain America: The First Avenger” and “The Avengers”, and Faris, widely regarded as being the best thing about such fare as “Observe and Report” and the “Scary Movie” franchise. She’s also been in some critically lauded stuff, including “Brokeback Mountain,” “Lost in Translation” and “Smiley Face.” Last year she was in “Cloudy with a Chance of Meatballs” is scheduled for a remake of “Private Benjamin” and is rumored to be in “Ghostbusters III.”

A production assistant on the platform was either being pointlessly obfuscatory or hopelessly dense Saturday. When asked who was in the movie, he shrugged and said “No one.” Tell that to their agents.

Faris was the only star on hand Saturday. Smaller than you’d think, which is what people always say about Hollywood stars, and resplendent in a shockingly red skirt-suit.

The film is due for release next year.