Mention the movie Fun In Acapulco and two scenes come to mind - besides the one where Elvis is diving off those cliffs (the most obvious, of course!) it's the one where he's riding a bicycle with the kid Raoul, who becomes his manager.
Together they are belting away "Mexico," and while I don't want to belittle child actor Larry Domasins musical efforts, I've always preferred the LP version featuring only the voice of Elvis. This despite the fact that the lyrics are incomplete because Elvis doesn't sing Raoul's parts, making the song sound strange.
Therefore, it was a pleasant surprise when FTD released their second CD in 1999 titled Out In Hollywood, containing alternate soundtrack recordings. It kicked off with Take 7 of "Mexico" which had Elvis singing all the lyrics, and I played it over and over.
This was how it was supposed to sound, with Elvis singing about senoritas, tequila, and shouting olé and caramba. Suddenly the lyrics made more sense and the song worked much better.
To me it's a mystery why RCA at the time decided to release take 5 with incomplete lyrics, obviously intended for use in the movie together with Raouls singing, which I guess was overdubbed on the set.
Maybe the record company thought it bad taste having Elvis singing about liquor, "one tequila makes you feel like, in to kiss a lovely senorita." (If that's the case then certainly Hal Wallis didn't have the same objections, having an eight year old kid singing the same thing!)
Or maybe it was just a mistake and the wrong take released. If so, 36 years went by until the mistake was corrected.