A set of remaining "loose ends" is casting a shadow on prospects for ratification of the U.S.-Soviet Intermediate-range Nuclear Forces treaty in time for President Reagan's summit trip to Moscow.

The four snags cited by Senate Majority Leader Robert Byrd, D-W.Va., include a U.S.-Soviet disagreement about the meaning of provisions designed to insure the United States against Soviet cheating.He and the other leaders say they are optimistic all the difficulties will be resolved, but they have firmly declared their opposition to rushing the ratification proceedings just so the work will be finished by the May 29-June 2 summit.

"This is not a delay," said Sam Nunn, D-Ga., chairman of the Senate Armed Services Committee. "This is an effort to do this thoroughly."

Since last December, when the superpowers signed the pact eliminating ground-based missiles with ranges between 315 and 3,125 miles, Reagan has hailed the verification and monitoring provisions as unprecedented sets of safeguards against Soviet non-compliance.

Having steered the pact through committee hearings, the administration is now eager for approval by the whole Senate in time for a formal exchange of ratification documents between Reagan and Soviet leader Mikhail S. Gorbachev at the summit.

Byrd told a news conference on Friday he would open the Senate debate on May 11, if the four obstacles are overcome. Joining Byrd and Nunn in the decision were the chairmen of two other important Senate committees: Claiborne Pell, D-R.I., of Foreign Relations and David L. Boren, D-Okla., of the Select Committee on Intelligence, who called the stumbling blocks "important loose ends."

The newest of the four problems identified by Byrd is a disagreement between the United States and the Soviet Union over the things inspectors of missile facilities will be permitted to see and where they may go to see them.

According to the State Department, Soviet experts believe the treaty permits inspection of weapons containers big enough to contain entire missiles. They also want to put off-limits some areas of three of their 133 facilities covered by the agreement.

The second snag, the senators said, was the need to get clarification from the Soviets, in writing, that the ban on intermediate range-missiles now in the superpower arsenal will prevent both sides from developing futuristic versions of these weapons.

In settling this dispute, the two countries would presumably need to define more precisely what is, in fact, a "weapons delivery system." The fear is that arms builders could devise a weapon they do not define as a missile but has the capabilities that today's missiles have.

Third, the senators are seeking assurances that the United States has the capability to verify the ban on futuristic weapons. And finally, they want a commitment from the administration that it is moving adequately and with enough money to upgrade satellite surveillance systems that help monitor the accord.