"A Party With Betty Comden and Adolph Green" was a happy choice for Arena Stage's annual benefit Sunday, which netted something over $30,000 for what is likely to be Arena's biggest deficit season so far.

Coming up June 5 is Arena's annual auction, when props, costumes, posters, trips, services such as catered meals and bartenders and surprises are part of two auctions. A "Silent Auction" at 4:30 begins in a tent on the lawn; at 7:30 p.m., there's the "Live Auction" in the theater. Food, drinks and ice cream will be on sale, and tickets at $5 may now be reserved at the box office (554-7890).

Even with full houses, Arena loses money each performance, as do all the non-profit theaters across the land, which is why benefits and auctions are as vital as gifts and grants. "Each year," says producing-director Tom Fichandler, "the pinch gets sharper."

Besides Vice President and Mrs. Mondale, the audience Sunday had another familiar face which had people stopping with that look of quizzical recognition.It was Lorne Greene, the "Bonanza" star. Houseguest of Frank and Jayne Ikard, Greene, who made his American bow opposite Katharine Cornell at the National in "The Prescott Proposals," allowed he'd like living in Washington. His wife, Nancy Deale, gave up acting after their marriage, went back to graduate school and just might be tapped for a Washington think tank.

As for Comden and Green, their sparklingly written and performed little revue will have a two-week run at Baltimores Morris Mechanic Theater May 16-28, and they'd like to follow its New York hit with a long tour. But first they have their latest project, a musical from the Hecht-MacArthur comedy, "Twentieth Century," to launch in the fall.

Richard Schechner has a novel idea for the "Mother Courage" noontime performances. The Performance Group will be giving in the Labor Department cafeteria May 9-13. Each noon about 45 minutes of the Brecht drama will be presented without scenery and lighting. By Friday, the entire play will have been completed. The uninterrupted version starts tonight at 8 and plays May 6, 7, 12, 13 and 14 in American University's Clendenem Theater.

Another novelty will be "Artucopia" to be presented at GWU's Marvin Center May 20-22. This series of three evenings embracing actree-poet-dancer Mary-Averett Seelye, the Contemporary Music Forum and sculptor Betty Klavun, has a university link: All the artists have had individual grants from the National Endowment for the Arts, to which the "Artucopia" is dedicated. The producer is John Yeo of Borrowed Time Productions; further details at 347-9414.

Folger Theater Group will preview "A Midsummer Night's Dream" May 10-12 to open on May 13 under the direction of Harold Scott, who staged "He's Got a Jones" last season. The cast will include Steven Zowicki, Al Corbin, David Cromwell, Erry Hinz and Elizabeth Perry, as well as some newcomers, Anthony Call, Andrew Lysander, Marcell Rosenblatt and Deborah Mayo. Phone reservations at 546-4000.

Arthur Miller, producer Robert Whitehead and director Arvin Brown will discuss the Eisenhower's new Miller play, "The Archbishop's Ceiling" May 14 at noon at the free arts symposium in the Kennedy Center's AFI Theater.