Trivia

Some distributors in the US re-cut and released this film with the title "Revenge from Planet Ape" in an effort to capitalize on the success of the Planet of the Apes (1968). A prologue was added in this cut version to make a connection--though dubious--between the two films. The prologue explains that 3000 years ago a simian civilization of super-intelligent apes struggled with man to gain control of the planet. In the end, man conquered ape after a brutal battle that saw him destroy the ape, his culture and society. After this battle man tortured and killed all the ape prisoners by piercing their eyes with red-hot pokers. One of the prisoners, who was also the leader of the apes, vowed they would return from the dead to avenge man's brutality" at a point in time before man destroyed Earth himself. This alternate prologue is available for viewing on the Blue-Underground DVD release.

The blind dead are never referred to as "Templar Knights" or "Caballeros Templarios" in the original Spanish language version. They are referred to as "los Guerreros de Oriente" ("The Warriors from the Orient").

The film was the first of Amando de Ossorio's "Blind Dead" films, spawning three official sequels: Return of the Evil Dead (1973), The Ghost Galleon (1974) and Night of the Seagulls (1975). Its success helped kickstart the Spanish horror film boom of the early 1970s.

The Blind Dead (Knights Templar) villains were unofficially resurrected in The Devil's Cross (1975), directed by John Gilling. The film was an influence on Mansion of the Living Dead (1982), directed by Jesús Franco. More recently, the Templar appeared in the unofficial, shot-on-video sequel Graveyard of the Dead (2007) (also known as "Graveyard of the Dead") and in supporting roles in Don't Wake the Dead (2008) and Unrated: The Movie (2009), two films by German director Andreas Schnaas. The short comic story "Ascension of the Blind Dead" appeared in the 2010 Asylum Press graphic novel "Zombie Terrors Volume 1", written by David Zuzelo with artwork by William Skaar. In 2015, Emma Dark and Merlyn Roberts co-directed an unofficial short film sequel, Island of the Blind Dead (2015).

Amando de Ossorio has stated that Gustavo Adolfo Bécquer's Gothic horror legend El río de las ánimas (1964) and George A. Romero's Night of the Living Dead (1968) influenced the creation of his film.