For people-watchers on the Washington scene, there were plenty of those "moments captured" at a glance, if not on film, at the reception last night opening "Pictures of People" at Georgetown Park.

The exhibit, through May 22, brings together about 120 photographs assembled from more than 5,000 that have appeared on the pages of People magazine in its eight years of celebrating personality journalism.

Nearly 200 guests were at the exhibit opener last night, looking at the photos dramatically displayed on 16 kiosks around the shopping mall's first level and themselves offering some snapshots of the Washington party circuit:

* John Anderson, who ran as an independent candidate before dropping out of the presidential race in 1980, didn't exactly give a direct answer when asked whether he has any plans for 1984 but had this wry observation:

"Once the appetite is whetted, the only sure cure for presidential fever is embalming fluid . . . I am looking round the bend of the tunnel that Mr. Reagan talks about. I see hope in two more years."

Keke Anderson, his wife, said she wasn't looking that far ahead.

"I barely can muster a thought on tomorrow," she said.

* An underwater photo of ex-president Gerald Ford, as he was coming up for air in the White House swimming pool, drew the attention of daughter Susan Ford Vance.

"I still travel a lot," said the former White House daughter as she and her husband, Chuck Vance, a former Secret Service agent, discussed his booming private security business.

"I worked on the trip that Time-Life arranged for 45 chief executives of business," Vance said. "We were in Poland when the unrest broke out and then in the Mideast. Imagine if terrorists seized a planeload of top business executives."

* Michael Evans, the White House photographer, was there for the showcase exhibit of work of other photographers. The White House circle also was represented by Julius (Bengtsson), who is Mrs. Reagan's hairdresser.

Julius, who has been doing Mrs. Reagan's hair since the California days, was remembering those times with Marilyn Lewis, who has moved to Washington from the California base of her 24-restaurant chain, which opened another Hamburger Hamlet in Georgetown in March.

People picture editor Mary Dunn was explaining how photographer Steve Northrup got the gag shot of Simon Bond, author of "101 Uses for a Dead Cat," as the target of a cat aiming a rifle with a "Bang" sign at the muzzle's end.

Dunn, who acknowledged that no self-respecting cat would pose for such a photograph, said that the cat had been hired from an animal trainer.

"And it took a long time to get the photo," she added with a sigh.