"They Went Thataway," a Western revival series scheduled to begin Friday, April 1, at the American Film Institute Theater, promises a number of off-beat attractions and gratifications for nostalgic devotees of this now neglected genre. The programming looks delightfully eclectic, beginning with a superlative double-bill - John Ford's "Stagecoach" with Sam Peckinpah's "Ride te High Country" - and then encompassing rarities, curiosities, musicals, comedies and special events along with the undeniable classics.

Film historian and collector William K. Everson has agreed to appear Sunday, April 3, at 6 p.m. with a survey of B" Western conventions and stars. The film-and-lecture program will include on feature, the 1932 "Mystery Ranch" with George O'Brien, plus excerpts from many others, emphasizing action sequences and stunt work.

Those of us who grew up on the Saturday matinee staples of the '40s may feel irresistibly impelled toward the triple bill "Hoppy, Gene and Roy" scheduled for Friday, April 22, at 8:30 p.m. At the moment the Gene Autry and Roy Rogers vehicles, "Robin Hood of Texas" and "My Pal Trigger," have been confirmed, although programmer Michael Clark is still pursuing his first choice among Hopalong Casidy adventures, "Hoppy Serves a Writ."

One of Ford's silent Westerns, the 1926 "Three Bad Men," shares a bill with Tom Mix's 1922 "Sky High" on Sunday, April 17, at 6 p.m. Laurel & Hardy's "Way Out West" doubles with Bob Hope's "The Paleface," scheduled to be shown in a vintage three-strip Technicolor print, on Sunday, April 24, at 6 p.m. The musicals are the elaborate, appealing "The harvey Girls" with Judy Garland and Angela Lansbury, set for 6:30 p.m. on Saturday, April 9, and 9 p.m. the following day, and the relatively modest, neglected but rousing "Calamity Jane," which boasts one of Doris Days most likable performances, on Saturday, April 16, at 6:30 p.m.

The AFI Theater has also announced the programs in the second part of its Jean Renoir retrospective, beginning Sunday, March 13, with a double bill of "Swamp Water" and "The Diary of a Chambermaid," two of his American productions, and concluding on Thursday, April 14, with "The Little Theater of Jean Renoir." The rarest item is perhaps "The River," a movie version of Rumer Godden's novel directed by Renoir in India in 1950. It will be introduced by the producer, Kenneth McEldowney, on Friday, March 25, at 8:30 p.m. and the following day at 6:30 p.m.

There are nothing but rare items in "Swedish Silent Treasures," a collection of very early features scheduled to open Friday, March 18, at 6:30 p.m. with "Erotikon," mauritz Stiller's legendary 1920 comedy of adultery. The features of Stiller and Victor Sjostrom dominate the series.

Peter Guber, the producer of the film version of Peter Benchleys "The Deep," opening Friday, June 17, at several area theaters, will appear at the Smithsonian's Museum of Natural History this Thursday at 8 p.m. to give a slide-and-lecture program on the movie company's experiences. Sam Kula, the former AFI archivist who now serves as director of the National Film Archives of Canada in Ottawa, will moderate a symposium about Canadian filmmaking tonight at 8 p.m. in the auditorium of the Hirshhorn Museum. The panelists are directors Gilles Carle, Peter Pearson and Robin Spry and cinematographer-turned-director Michel Brault, probably best-known here for his work on the Claude Jutra films, "My uncle Antoine" and "Kamouraska."

The new Woody Allen comedy, "Annie Hall," now has a Washington opening date - Wednesday, April 27 - although the precise number of locations seems to remain in doubt. At any rate, it will not be playing at the Avalon, which has been The House of Allen ever since "Bananas." The mystery thriller "Audrey Rose" has already been booked at the Avalon by the same distributor, United Artists.

This break with local tradition should not be construed to signify anything about the relative quality of the films. If anything, the grapevine on "Annie Hill" seems much more reassuring. Although the finished films remain to be seen, this slack movie season may justify passing along optimistic rumors about upcoming attractions; for what it's worth, the New York grapevine has begun to sizzle about both "Annie Hall" and Martin Scoresese's "New York, New York," which is headed for the Avalon, on Wednesday, June 29.