Distributors of the movie "Star Wars," one of the largest money-earning films of all time, contended here yesterday that a U.S. Patent Office decision may cost them "untold millions of dollars" in potential earnings in foreign countries.

In a suit filed by Twentieth Century Fox Film Corp., distributors said the official filing date of certain "Star Wars" patents leaves on opening for persons in foreign countries to copy famous "Star Wars" characters and designes on such items as toys without the distributors' permission.

The suit, filed in federal court, asks U.S. District Judge Gerhard A. Gesell to order the U.S. patent commissioner to change the filing date under various patent regulations.

Unless the change is ordered, according to attorneys who filed the suit, there could be unauthorized foreign versions of the robots R2-D2 and C3PO, two types of spacecraft and Darth Vader's mask and helmet costume.

Patent applications for those items were filed last Sept. 12, but were considered incomplete by the patent office because of the inability of the company to locate one of the inventors of each of the design applications, according to the suit filed by Arlington attorney Herbert Cohen.

The applications were approved by the patent office on Jan. 19, but assigned an "official" filing date of the earlier incomplete application, Cohen continued.

The September date prevented the company from filing the proper foreign patent applications within prescribed time limits, the suit asserts.

Without the foreign patents, it will be "open season" in those countries on the familiar designs, one attorney in the case said.

The Star Wars attorneys already have appealed the issue through the U.S. Patent Office, but the patent agency said "a filing date may not be changed to overcome a problem with respect to a license for foreign filing."

Attorney Cohen said the optential losses to Twentieth Century Fox concerning foreign patent rights to the space swashbuckler could be "astronomical."

Cohen, who said he has seen the movie twice, said it appears to be well received in foreign countries as well as in the U.S. Star Wars company officials a said in Hollywood that no current figures were available, but the movie has grossed at least $400 million worldwide.

The movie, which has set box-office records since its release last summer and has prompted takeoffs, spinoffs, Phonograph records, and contests to see who could see it the most times, is no stranger to courtrooms either.

In at least one other pending action on the West Coast, two firms filed lawsuits seeking more than $23 million in damages for alleged unauthorized sales of Star Wars merchandise in the U.S.