Trapped. Trapped. Trapped like a dope smuggler in a Turkish prison. Just after 10 o'clock last night, characters in the film "Midnight Express" on ABC television were plotting their escape from a hellhole, but CBS and NBC and anybody watching them were stuck for an hour at the Baltimore Convention Center for a presidential debate short on debate and short on presidential.

CBS and NBC had agreed to carry the League of Women Voters' affair starring John B. Anderson and Ronald Reagan, but ABC had decided not to on the grounds that without the participation of President Carter it wouldn't be much of an event. How right they were.

It's just too bad ABC had such a dreadful movie as an alternative. Viewers had to decide whether to be locked up with Anderson and Reagan and the stiflingly rigid debate format or with this very dumb American kid who tried to smuggle several pounds of hash out of Turkey and was sentenced to forever in the hoosegow for his trouble.

"The questioners are limited by the constraints of the format," confessed moderator Bill Moyers right off. Then he cautioned the Baltimore audience, "Please do not applaud or express approval or disapproval during the debate," as a precaution by the League to discourage excitement of any kind. This, however, was an occasion in which such additional wet blankets were totally gratuitous. Even an empty chair would have been a pleasant distraction.

The networks had also been instructed by the League not to have any reaction shots of the audience, and Walter Cronkite said they were turning out the lights on the crowd just in case. But the daring director did get one shot of Nancy Reagan and Keke Anderson. Fortunately, they did not seem to be reacting to anything.

Reagan came off best in the debate, with his dappled apple cheeks and glistening misty eyes, but he occasionally stammered and hesitated as if slightly unnerved by his current reputation as a verbal Gerald Ford, prone to bumbles and feet-in-mouth. However, Anderson was clearly coming on too strong, his eyes shifting distrustfully around the hall, his tone strident and nagging like a TV evangelist urging repentance or a Welby doctor plugging a new diet book on the Dinah Shore show.

Naturally, there were several references to Carter's absence and the debilitating effect that that had on the debate. Anderson was more aggressive than Reagan but not necessarily more effective. When Reagan paused and searched for words on the abortion issue, even this hesitancy seemed more attractive and temperate than the rat-ta-tat-tat of the Anderson machine gun. Reagan referred to his opponent repeatedly with a chummy, if patronizing, "John," but Anderson stiffly referred to his opponent only as "Governor Reagan."

Of course, what could Anderson call him? Ron? Ronald? Ronnie? There weren't many choices.

But, really, the event was so softcore -- as news, as entertainment, as "real people" -- that one was almost forced to keep one eye on "Midnight Express" as the evening wore on and questions were repeately answered but with the inevitable hot air. In fact, as one questioner was asking that the candidates show "responsiveness to the questions rather than repetitions of your campaign addresses," it was being reported on ABC that some poor immate of that Turkish prison had suffered a severe hernia and lost a testicle.

At the point where the hero of the film was telling his Turkish captors, "You're all pigs," Reagan was saying we can solve the military problem if we "just recognize human nature and how we make everything work in this country when we want it to work."

When Reagan and Anderson were bickering over the merits of the MX missile, ABC was offering the solace of "double protection" from a toothpaste during a welcome commercial interruption of the movie. Just as Anderson was addressing himself to the "leaking water of Pittsburgh," the Turkish prisoners were digging in the sewer in an effort to set themselves free.

And by the end of the debate, which was a long time coming, one prisoner had gone completely nutty and was being shipped off to facilities for the criminally insane, joining fellow prisoners in an aimless walk around and around in circles just as Reagan was saying, "For 200 years we've lived in the future" and fashioning once more for us his vision of "a shining city on a hill," presumably not Pittsburgh.

This was during the "closing remarks" section of the program, which Reagan whimsically began by saying, "Before beginning my closing remarks here, I would just like to remark . . ." A moment later, Anderson was addressing the commentator as "Mr. Moyer" and then turned to address the viewer with intimidating questions like "Do you really think that our economy is healthy?" and intimidating answers like, "I don't think you do think that."

And the prisoners continued to march around and around and around.

Moyers said at the conclusion that, "For all the limitations of the form, the debate may still have had some value." Perhaps it did as a public relations device for the League of Women Voters or for the City of Baltimore, where boosters seemed to look upon it as a great civic coup. Perhaps it aided the Carter candidacy in that his absence indicated he was above it all. But it probably had the most beneficial effect on the ratings of "Midnight Express."

Probably the worst example of inflation during the whole evening was Anderson's estimate that "221 million people are watching the debate."

His figure was probably just about 200 million off. Those folks needn't feel the least bit guilty this morning.