Why, yes.  The Academy "forgot"….

Farrah Fawcett (who was phenonmenal in Extremities)
Bea Arthur
Ricardo Montelban….

Why weren't they included?  Not an oversight.  They just didn't make the cut:

The In Memoriam segment can be the most moving part of the Oscar telecast. It’s also the toughest to produce.

"It is the single most troubling element of the Oscar show every year," says Bruce Davis, executive director of the Academy of Motion Picture Arts and Sciences. "Because more people die each year than can possibly be included in that segment."

Davis’ office keeps a running list of academy members and others in the movie business who have passed since the previous year’s segment was compiled. Then, a few weeks before the awards, he and a small committee of academy officials whittle the list of more than 100 names down to the 30 or so folks who will be included in the show’s memorial — from the famous faces viewers at home are sure to recognize to the behind-the-scenes workers familiar only to academy members.

"It gets close to agonizing by the end," Davis says of the annual meeting. "You are dropping people who the public knows. It’s just not comfortable."

Oscar’s In Memoriam montage began in the early 1990s and other awards shows followed suit, including the Screen Actors Guild Awards, Grammys and Emmys — all of which go through the same painful process every year.

"It’s a killer because we have hundreds of members that pass each year and we can’t get them all in," says SAG Awards producer Kathy Connell.

The film academy gives its final list of in-memoriam honorees to the producer of the segment just days before the big show. Chuck Workman, who is producing the memorial montage for Sunday’s telecast, says he was working with a temporary list until last week.

Many of the names made the final cut, he says, but some did not.

"It’s a constant balance for the academy," says Workman, who has 20 years of experience making film montages for the Oscar show. "They do try their best, but there’s only so many spots."

Uh-huh.  So that's why Arthur Canton, Public Relations, was included, but Maurice Jarre (9 Oscar nominations and 3 wins), Henry Gibson (nominated for his work in Nashville), Farrah Fawcett, Bea Arthur and Ricardo Montelban were not.