THE BIOGRAPH'S Japanese series continues this weekend with two films by Nagisa Oshima, In the Realm of the Senses (the first feature by a major director to contain explicit sex scenes) and the hauntingly effective Merry Christmas, Mr. Lawrence.

Then Tuesday through Thursday, the series offers Kihachi Okamoto's The Emperor and a General (with Toshiro Mifune) and the Washington premiere of Yasujiro Ozu's first postwar film, 1947's Record of a Tenement Gentleman. For showtimes, call the Biograph at 333-2696.

The Charlie Chaplin film City Lights will screen Tuesday at 8 in the Baird Auditorium of the Museum of Natural History Building. Another of his films, The Gold Rush, will screen August 20, same time, same place. Both will be presented with music tracks; the cost to see both films is $7 for members of the Smithsonian Resident Associate Program, $10 for non-members. Individual screening tickets are $4 and $5.50. Call 357-3030.

Good news this week from the American Film Institute Theater: After years of enduring a parking situation that often resulted in members paying more to park their cars than to see a film, the theater has entered into an agreement with the Watergate Hotel. Now you can park at the hotel, pick up a card at the theater box office and present it before drinking or dining at the Peacock Lounge or Les Champs restaurant. You get free parking, and they'll even throw in a free drink, a "summer cooler." They say there's no minimum order. For more information, call 785-4601.

Roth Theaters, DC 101 and the Kemp Mill record store chain have organized an expansive promotion for Orion's new horror comedy The Return of the Living Dead. Friday between nine and midnight, the Kemp Mill location at 7310 Baltimore Boulevard (Route 1 to you townies) in College Park will host a pre- screening party. Featured will be in-store discounts, distribution of 101 pairs of tickets to the premiere and WDCA's own Count Gore De Vol (Dick Dyszel) mixing it up with the masses. Close to the stroke of midnight, everybody will traipse down the road to the Roth's College Park house (7242 Baltimore Boulevard) for the movie. For more information, call Roth's at 587-8450 or DC 101 at 828-9932.

"The Return of the Living Dead," which was co-written by John Russo (who wrote "The Night of the Living Dead" in conjunction with George Romero) and Dan O'Bannon ("Alien," "Blue Thunder"), opens commercially next Friday.

In a related item, Roth's has found a couple to be married immediately before the sneak preview of Columbia's The Bride, a remake of "The Bride of Frankenstein," next Thursday at its Seven Locks location in Potomac. They are Christina Cheplick, a Ph.D. candidate at the University of Maryland, and Dr. George Dillon, an English professor at the same school. DC 101's Greaseman will give away the bride. (If you want to be there for the blessed event, the radio station will be giving away a limited number of tickets on the air on Tuesday only.)

What prompts a couple to get hitched in such a fashion? "Marriage is a serious matter," says Dillon, who's due to publish his fourth book early next year. "But weddings don't have to be long-faced." Kind of a coincidence that he's a doctor, you say? Try this: The bride hails from Kluj (the second largest city in Rumania), which is located in the district known as Transylvania.

According to the Washington-Based Motion Picture Information Service, the area's 10 top- grossing pictures for the week ending August 1, were, in descending order, Back to the Future (holding at 18 locations in its first month of release); National Lampoon's European Vacation (debutin strongly at 19 houses); Silverado (staying on 17 screens in week three); The Black Cauldron (at 13 locations in its first week); Cocoon (remaining at 17 screens in week six); E.T. The Extraterrestrial (at 14 screens); Mad Max Beyond Thunderdome (at 21 screens in week three); St. Elmo's Fire (at 12 screens in its fifth week); Rambo: First Blood Part II (moving from 14 to 16 locations in week 10); and The Man With One Red Shoe (at 15 screens in its second week).

Heavy exposure of a rollicking TV trailer apparently more than made up for the lack of advance screenings as "National Lampoon's European Vacation" surprised everyone by collecting $12 million and change in its first three days of release. That's the largest non- holiday opening of the summer, and the third largest debut overall (only "Rambo" and the Bond picture "A View to a Kill" did better).

At its national pace of $66 million-plus in only 26 days (at over 1,500 theaters), it won't be long before "Back to the Future" blows past the $100 million mark -- only the second picture to do so this lackluster season ("Rambo" was the other, currently perched at $134 million).

While The Goonies, Cocoon and Fletch are within hailing distance, only Ron Howard's "Cocoon" is seen as having a serious shot at $100 million.

In international production news (gleaned from various trade papers): Randal Kleiser, director of "The Blue Lagoon" and "Grease," is now the director of The Navigator, a Disney project that was originally to have been made by Brian De Palma . . . Jerzy Skolimowski's first American film, The Lightship, will have its world premiere at the Venice Film Festival later this month. The picture, which stars Robert Duvall and Klaus Maria Brandauer, is one of two official U.S. entries (the other is Prizzi's Honor) . . . Even though Leonard Nimoy grew to hate being associated with the character of Mr. Spock, he parlayed the fame into a director's job on the last Star Trek film; now Anthony Perkins has done much the same thing by getting himself hired to direct Psycho III, which is filming at Universal Studios. Guess who stars as the indefatigable Norman Bates? . . . Title of the week goes to the independent production Breakdancers from Mars, filming in California, New York and Utah . . . After a lengthy hiatus from the big screen, Alan Alda is directing and starring in Sweet Liberty for Universal; he scripted the film as well, which co-stars Michael Caine, Michelle Pfeiffer and Bob Hoskins . . . Sylvester Stallone is dong O.K.; in addition to the payoff from "Rambo," he's putting the finishing touches on the next chapter in the Rocky saga and will receive a reported $12 million to star in Cannon Pictures' Over the Top, to be directed by Menahem Golan, Cannon's chairman. (That salary figure, incidentally, represents just under half thelm's entire budget.) . . . The American National Theater's own Peter Sellars has a supporting role in Columbia's Happy New Year, starring Peter Falk, Charles Durning, Tom Courtenay and Wendy Hughes under the direction of John Avildsen.

PAGES OF FILM HISTORY -- Happy birthday this date to boxer-actor Ken Norton and comedian David Steinberg. Robert Zimmerman changed his name to Bob Dylan on this date in 1962, and it was 16 years ago that Roman Polanski's wife, Sharon Tate, and four others were murdered by Charles Manson's "family."

Those celebrating on Saturday include Noah Beery Jr., Jeff Corey, Rhonda Fleming, Jimmy Dean, Eddie Fisher, Jethro Tull's Ian Anderson and Ronnie Spector (of Ronettes fame). "Candid Camera" premiered 37 years ago Saturday.

Sunday's birthdays include those of Lloyd Nolan, Carl Rowan, Mike Douglas and Virna Lisi. Eugene Lauste patented the first sound- on-film process on that date in 1906. And ABC TV's first regularly scheduled newscast went on the air August 11, 1948.

Eddie Cockrell is a freelance film consultant and teacher. His "Insights on Film" is heard Mondays at 5:30 p.m. on WGMS AM & FM.