Oliver Reed's voice is not heard; he's dubbed throughout by another (anonymous) actor attempting to sound like Reed's normal voice. Reed's own voice is heard in the film's trailer, where he adopts a very camp lisping French accent.
Richard Greene (Robin Hood) was the only actor to reprise his role from The Adventures of Robin Hood (1955). The other roles were played by an entirely new set of actors.
The movie, as it is now, is without its original opening sequence, which was cut; apparently. It depicted the Lord being murdered whilst on crusade and his squire fleeing to Sherwood Forest on his horse. As it is, the movie now opens with the squire riding into the forest on horseback and his identity is never revealed.
Desmond Llewelyn, Nigel Green, Richard Pasco, Brian Rawlinson, Charles Lamb and Ivor Collin all appeared in The Adventures of Robin Hood (1955) whilst Terence Fisher directed eleven episodes of the series.
Nigel Green (Little John) and Richard Greene (Robin Hood) would both later play Fu Manchu's arch-nemesis Sir Denis Nayland Smith in films starring Christopher Lee as the Chinese criminal mastermind: Green in The Face of Fu Manchu (1965) and Greene in The Blood of Fu Manchu (1968) and The Vengeance of Fu Manchu (1967).