A special effects explosion on the set of a new Jack Palance movie went awry yesterday, injuring six stunt men who were burned on their hands and faces, police said.Filming was under way on Terminal Island about 3 a.m. when a fireball from the blast was channeled toward the stunt men rather than upward, said Los Angeles Harbor Police Lt. Martin Renteria. The victims were filming a scene from the Cyborg II production company film “Glass Shadows.” Palance was not present at the time of the blast, Renteria said. A call to Cyborg II’s office was not answered yesterday morning. The script called for the stunt men to be catapulted into the air immediately after the explosion. Renteria said it was unclear just why the fireball billowed toward them rather than skyward as planned. The men were standing in a field of 12- to 13-foot chunks of scrap metal when the fireball jumped back, Renteria said. Four of the men were taken to the burn unit at Sherman Oaks Hospital, where they were in stable contition, being evaluated for burns on their hands, faces and ears, said hospital spokesman Larry Weinberg. Two others were in good condition at the Torrance Memorial Hospital burn unit , said nurse Naiwei Chang. Weinberg identified the men at Sherman Oaks Hospital as Jeff Habberstad, Merritt Yohnka, Brian Smrz and William Morts. Those at Torrance Memorial were not immediately identified.