He doesn't even know the Catholic sign of the cross. After the Reagan Library service he and his wife approached the coffin. While his wife correctly blessed herself - temple, heart, left shoulder, right shoulder - he did a right shoulder, left shoulder move. In his Hollywood mind-set I guess he figures any screw up can be fixed with another 'take'.
That one you could proably let slide. I believe the Greek make the sign of the cross right to left, rather than left to right. Maybe he was thinking Greek Orthodox.