Campfire. Festival runs throughout Saturday, Sunday and Monday starting at noon at Passim, 47 Palmer St., Harvard Square. Tickets are available as $25 festival passes – down five dollars from last year – and $10 daily passes. Harvard students get in free.

Passim’s twice-a-year homegrown music festival runs throughout the long Labor Day weekend, starting Friday and running noon to midnight Saturday and Sunday and noon to nearly midnight Monday – some 75 acts in all. The festival aims to develop talent and celebrate the local music scene, with organizers saying shows typically blur the line between performer and audience member. The all-ages event, now in its 16th year, has a full schedule here.

“The Godfather” and “The Godfather: Part II” at The Brattle Theatre, 40 Brattle St., Harvard Square. Tickets are $8 general admission for one film or $12 for the double feature.

These Francis Ford Coppola films from 1972 and 1974 are not only masterful and enduring cinematic accomplishments; they literally changed the world. For one thing, they made it impossible to claim that the sequel is always worse than the original (a feat soon to be repeated by “The Empire Strikes Back.”), but they also changed how films were released. Until 1972, “event movies” such this Mafia crime epic cost more to see, but “The Godfather” was priced the same as run-of-the-mill flicks and drew huge box office response, says Barak Orbach, a professor of law at the University of Arizona who co-wrote a study on variable pricing in 2006. When other studies wanted to duplicate that response, the system of “A movies” and “B movies” broke down – until Coppola released “The Godfather” Part III” in 1990 and introduced the world to the “F movie.”

The “Godfather” films are showing as part of a retrospective on the works of cinematographer Gordon Willis, the so-called “Prince of Darkness” for the way he shot light and shadow.

“Grease” by the MIT Musical Theatre Guild from 8 to 10:30 p.m. Saturday and 2 to 4:30 p.m. Sunday at the Massachusetts Institute of Technology’s Kresge Auditorium, 48 Massachusetts Ave. General admission is $15, payable at the door.

This virtually inescapable musical about high school love in a mildly mythological 1950s had an eight-year run on Broadway, a Hollywood production with John Travolta and Olivia Newton-John, two Broadway revivals and innumerable school and community productions. But just in case you wanted to see it again and get “Summer Nights,” “Greased Lightning” and “Beauty School Dropout” stuck in your head (or your kids’ head) for the next month, this is your chance. (Also every Friday, Saturday and Sunday through Sept. 13.) Information is here.

The Nothing Is Not Ready Circus by Bread & Puppet Theater from 3 to 4 p.m. Sunday at Magazine Beach Park (along the Charles River at Magazine Street, across from Trader Joe’s and the Micro Center), 719 Memorial Drive. There is a pass-the-hat donation requested.

The shaggy Bread & Puppet Theater troupe descends from Vermont occasionally to remind everyone what hippies look and act like, and also what fun combined with political discourse feels like. Sourdough rye bread will be served and cheap art will be made available (with a recommended donation) after the performance, which is presented with assistance from the Cambridge Arts Council and Cambridgeport Neighborhood Association.

The Bread & Puppet Theater has its own description for and indication of what you can expect Sunday:

Nothing Is Not Ready Circus is for the not-yet-existing upriser masses and their kids who need to practice their upriser skills by teaming up with butterflies, cockroaches and elephants. Lions, horses and dogs are also employed to invent the correct rhythmical patterns that fight planetary destruction. The boot flags of the 15th century peasant revolution lead the way, with a lively brass band for accompaniment. Bread & Puppet’s “Circus” acts can often be politically puzzling to adults, but accompanying kids can usually explain them.

For information, call (617) 286-6694.

The Cambridge Footlights U.K. comedy troupe at 7:30 p.m. Sunday at ImprovBoston, 40 Prospect St., Central Square. Tickets are $20 (or $16 for students at the door).

The Footlights have a 130-year history as a launching pad for comedy careers, including those of the internationally famed John Cleese, Hugh Laurie, Emma Thompson, Mitchell and Webb and Sacha Baron Cohen. This one-night-only show by the not-yet-too-famous-to-see members, “Real Feelings,” is an hour of new sketches, surrealism and satire that the troupe is bringing around the world. Information is here.