Dozens of Oklahoma celebrities from the worlds of sports and entertainment will participate in ceremonies opening the 1989 U.S. Olympic Festival today in Oklahoma City. Among them are Reba McEntire, Roger Miller, Patti Page, James Garner, Curt Gowdy and Mickey Mantle. Also on the bill: Bob Hope and former President Ronald Reagan. Besides kicking off the multi-sport event (which is held in non-Olympic years), today’s spectacular is part of Oklahoma’s yearlong centennial celebration. The pomp and pageantry will be carried on the Nashville cable network, beginning at 6 p.m.