Yes, there are different mixes of several of the songs! In fact, the film seems so intentional about highlighting them that it almost seems like they might intend to release them at some point. Maybe just wishful thinking.
It's part of their 'artistic wash marketing strategy' to lead you believe that more tracks exisit and that you have to collect them. I will bow down to the addiction that is collecting.
Would anyone be interested in creating a SOE companion master list of official tracks not on the Super Deluxe? This would include promos, remixes, Spotify singles and such?
Since it's easy for me in the back-end of the site to grab this:
Get Out of Your Own Way (Radio Edit)
Get Out of Your Own Way (Switch Remix)
The Blackout (Jacknife Lee Remix)
The Blackout (Live from Amsterdam)
The Little Things That Give You Away (Live from Seattle) - U2Com Streaming
The Little Things That Give You Away (Recorded at Neptune Valley) - Spotify Singles
What's Going On (Recorded at Neptune Valley) - Spotify Singles
You're The Best Thing About Me (Acoustic Version)
You're The Best Thing About Me (Sci-Fi Soul Mix)
You're The Best Thing About Me (Live from Sao Paulo) - Amazon U2 Experience
This does not include the alternate mixes in "Liner Notes" as they are partials. The links to the discography / video entries for these are available here:
http://www.u2songs.com/news/soe/