The seventh Spartakiade, the quadrennial finals of the mass-participation "National Games of the Peoples of the U.S.S.R.," officially opened today with a grand splash of fanfare and a peculiarly Russian proclivity for excelling at pomp and fouling up circumstance.

The first full day of the colorful Soviet sports festival, which has gained worldwide attention as a preview of the facilities and organizational apparatus for the Olympics that will be held here next summer, underscored both the Soviets' peerless ability to stage memorable pageants and their seeming inability to deal with such mundane details as proper organization of a footrace.

The multinational parade of competitors and torch-lighting ceremonies were a triumph of sight, sound and propaganda - a rousing two-hour extravaganza of marching, flag-waving, gymnastics, folk dancing, patriotic songs and slogans and general celebration of the diverse cultural, ethnic and athletic heritage, of course, by Big Brother and the sports-loving Communist Party.

The Soviets are unsurpassed at choreographing and orchestrating this type of spectacle, which seems to combine equal measures of halftime at the Super Bowl, the Macy's parade, a Cossack dance troupe, a production number of a 1930s musical, Radio City Music Hall and the latest Communist Party congress.

From the time 400 track-suited men waving red flags and 1,200 leotard-clad women bearing multicolored balloons entered the jampacked, 103,000 seat Lenin Central Stadium to begin the festivities until 3,000 doves were released over a vast portrait of Vladimir Ilich Lenin in the grand finale two hours later, not a trumpet or a tumbler or a trampolinist was out of place.

Formation after formation - from the parade of teams representing the 15 republics of the Soviet Union, various cities and clubs and 87 foreign countries to the presentation of flowers to assembled government and party leaders by children of leading sports schools - was synchronized to perfection.

But when it came to getting the starting lists for race heats and other competitions properly updated and distributed, and athletes on right fields at the right times, the presentation was not quite so flawless.

For example, Edwin Moses - the world's premier 400-meter hurdler - went home to the United States with an injury after frunning in Switzerland last Wednesday. However, when the 400-meter heats were held today, his name went up on the big electronic scoreboard at Lenin Stadium and an American wearing his No. 825 appeared in the assigned lane.

The mysterious Moses reached the finish line last, having fallen flat on his face at the last hurdle. He turned out to be middle distance runner Stan Vinson, who has praticed hurdling at home in Chicago but never had attempted the event in competition. He was entered as a substitute for "on-the-job" training, but some Muscovites in the stands never realized that they had not seen Edwin Moses go down to ignominious defeat.

A whole group of modern pentatthless, including the usually dominant Soviets, showed up all the shooting range to compete, only to discover that they had been directed to the wrong range.

"The Russians are trying their very best to put on a first-rate competition," the British modern pentathlon coach, Bob Bright, was heard to say, "but their very best isn't proving good enough."

This comment came on the heels of joint praise and criticism of the facilities that have been built for next summer's Olympics and are being used during Spartakiade. Generally speaking, there has been praise for the athletic fields and arenas but brickbats for the accompanying facilities for creature comforts.

"They've built 20th and 21st century sports arenas, and equipped them with 19th century toilets," complained one coach of an East European modern pentathalon team, noting that the new fencing hall was "magnificent" but that its bathrooms were wholly inadequate, given to flooding and embarrassingly lacking in privacy.

Moreover, some European sports officials and journalists were grumbling about snafus in obtaining visas to enter the U.S.S.R.

Several athletes - including American 800-meter man Steve Scott - did not show up and were scratched from races, apparently because of visa problems.

However, the U.S. men's track and field coach, Jimmy Carnes, whose Spartakiade team was weakened considerably by last-minute dropouts, absolved Soviet authorities of blame in the foul-up that left some 30 American athletes, who did not have visas, sitting on their suitcases at Kennedy Airport in New York as their plane took off for Moscow.

"It wasn't the Russians' fault," said Carnes. "It was just a complication arising from the fact that many of the athletes were traveling around, and we didn't get the visas sent to where they were. Next year, we'll know to get started early."

Some Western officials and journalists criticized the Soviets for heavy-handedness in inviting foreigners to complete alongside Soviet athletes in the Spartakiade for the first time.

Spartakiade is run by the U.S.S.R. Sport Committee, not the Olympic Organizing Committee, and so Olympic rules did not prevail in issuing invitations. Countries such as Israel, Chile, New Zealand, Nicaragua and China, not in favor at the Kremlin, pointedly were not invited. Meanwhile, scores of Third World countries, from Algeria to Zambia, not only were invited but their teams subsidized by the U.S.S.R. politcal favor.

"I think that gives us an idea how the Soviets will treat sensitive political issues next year," said one American. "I bet they don't let Israel in in 1980 either."

"Yes they will," countered a veteran observer of the political ways of the U.S.S.R. "They have a lot at stake and they're not going to risk messing up the Olympics. They'll play it straight by the book and let the Israeli team in.

"The only questions are, how they will treat the Israelis when they get here and how many Israeli spectators they'll give visas to."

So when numerous debates on how the Soviets will fare as Olympic hosts, and so they will continue.

But the 103,000 spectators at Lenin Stadium today, and hundreds more outside who pressed against gates to try to get a glimpse in, were more interested in the glittering ceremonies opening the final two weeks of Spartakiade, a massive national competition that the Soviets say involved more than 100 million participants in its earliest stages.

The huge audience included many prominent party and government officials who arrived in seemingly endless waves of black government cars - from long, sleek 1979 Limousines to the Volga sedans that are the most popular models for Moscow taxis. In this supposedly classless society, these were all parked in a special lot, in strict order of protocol. CAPTION: Picture, Mishka the Bear is protrayed in stands as Spartakiade opens. AP