Sir Ian McKellen was rushed to the hospital after falling off stage during a live performance in London, RadarOnline.com has learned. The legendary performer, 85, reportedly lost his balance and slipped as he was acting out a fight scene in Player Kings, an adaptation of Shakespeare’s Henry IV, at the Noël Coward Theatre Monday evening. BBC News said McKellen “was circling a battle scene involving the Prince of Wales and Henry Percy, when he fell off the front of the stage.” When the lights came back on, the outlet said, McKellen “cried out and staff rushed to help.” Paul Critchley, an audienc…