R2 Spanish -release contains the original "Spanish version", but doesn´t have English subtitles.

General notes about "French version" vs. original "Spanish version" (this movie was made in two completely different versions simultaneously, featuring a French and Spanish cast, respectively):

-"Spanish version" is approx. 2:32 min longer. The soundtrack on the Spanish version (credited to Pablo Villa) is completely different and much more effective. It is louder, and uses eerie organ music and "moans" instead of the bland electronic score on the "French version".

-There are 4 sequences which have been "re-filmed" for the "Spanish version", basically using the same story outline, but different actors (Lina Romay, Eduardo Fajardo, etc.). They are all longer (and better) than their English/French counterparts - totalling 21m 50s compared to 16m 08s (an additional 5m 42s overall).
1) The first is immediately after the opening credits and shows Lina Romay waiting outside the house in a jeep whilst Eduardo Fajardo tries to extract information about the location of the oasis from Robert's father before killing him. (Spanish = 6m 38s, English = 4m 04s).
2) The second is after about 30m and shows the arrival of the search party at the oasis. They set up camp and attacked at night by the zombies. Lina Romay is graphically killed and her intestines removed. Eduardo Fajardo escapes although he is bitten. The English/French version is nowhere near as graphic (a few brief shots of the zombies are the same in bother versions). (Spanish = 12m 07s, English = 9m 28s).
3) The third is after about 45m and is just a brief sequence in which Eduardo Fajardo wakes up in the jeep and walks off. In the English/French version the man wakes up in bed before getting up. (Spanish = 23s, English = 16s).
4) The fourth is shortly after the above sequence and shows Eduardo Fajardo laughing maniacally as he starts to turn into a zombie from the bite on his neck. He eventually falls convenietly onto a bed of straw before being burnt. There are several cut-away shots of the students watching this from the English/French version. (Spanish = 2m 42s, English = 2m 20s).
-After just over 60m there is a 3m 17s sequence of a couple of the students making love in their tent in the oasis (Inga and friend). This has been edited out of the Spanish print entirely.
There are 2 further brief sequences not in the Spanish version: 10s after 75m - the girl student (Inga) carrying a petrol can being grabbed by the ankles by a zombie emerging from the sand, and 7s after 76m in which the zombies surround her and bite her leg.
-One sequence lasting 46s of a series of shots of the zombies approaching, close-ups of worms on their faces, and shots of the oasis, is in a different place in the Spanish version (after 79m instead of 74m).
-Finally after 81m there is one extra shot lasting 12s in the Spanish version showing the zombies disappearing into thin air in front of the oasis.
-Of course the opening credits are completely different on both versions, although they last the same time - 1m 10s. The Spanish ones are in red lettering and play over a close-up of a zombie's face, whilst the English/French ones are in white lettering over a shot of the town. The Spanish print ends with 15s of additional credits after "Fin" which credit Jesus Franco as "montaje" and Lina Romay as "ayte. de montaje".
-The only other difference I noticed was the fact that there is more narrative voice-over during the war flashback sequence.
-To summarise then, the Spanish version has 22m 02s of footage not in the English/French version, but is missing 3m 34s of original footage and 16m 08s of alternate footage, giving a total difference of 2m 20s + 15s at end - 3s minor jumps = 2m 32s. (This info is from Francis Brewster/"Mondo Erotico").