According to Skinner & Verhoeven, it was played as part of a short, impromptu tournament on either the 1st (the date of the first round) or 2nd of December 1941:

<The tournament was also reported briefly in the Madrid newspapers <Arriba> and <Ya> over the period the 2-6 December. There are ambiguities of dating in the reports, so the information needs to be treated with some reservation. For instance, although the start and finish dates for the tournament are reasonably certain, it is possible that Alekhine's first two games may have been delayed and played on the same day. One report indicates that they may also have been played in reverse order. This would be consistent with Alekhine arriving late and having to play his first round game in the afternoon, following the conclusion of the second round.>

They give Black's name as Isidro Naharro and confirm that the 16-move version is the correct one.

Moran's book on Alekhine identifies the main source of the confusion surrounding this game:

<This game's rediscovered, original signed scoresheet corrects the error in both <¡Legado!> and <Alekhine's Best Games, 1938-1945> (Game 4A), which reduce this to a 12-mover from 1940 (a year Alekhine bypassed Spain) against Navarro - an almost identically named opponent whom Alekhine defeated in an above mentioned 9-board clock exhibition. Alekhine named the wrong player when citing the game from memory for <¡Legado!>.>

Unfortunately, Moran introduces confusion of his own, because he gives the date of the 9-board clock exhibition as 2 December (i.e., possibly the same date as Alekhine's first round tournament game with Naharro), whereas Skinner & Verhoeven date it later to the 17th December. Moran's book also has <Dr Naharro> in the main text, but <Miguel Navarro> in the index. Maybe Miguel was the clock simul opponent.