olePigeon said:

Now, my dad also remembers it being undubbed when he saw it on a plane (it had subtitles.) Do airlines get different versions than regular DVDs?

Yes, they do on occasion. Others will probably weigh in with more detail but The Rock, Fantastic Four(2005), The Abyss, The Truman Show and allegedly BTTF 2 are just some of the films to have received alternate versions for airlines.

Here’s some articles on the topic:

https://stephenfollows.com/in-flight-movies/

http://www.rogerebert.com/rogers-journal/director-pulls-credit-after-airlines-cut-film

http://www.telegraph.co.uk/news/uknews/1549215/BA-airbrushes-Branson-from-in-flight-Bond-film.html

http://www.newnownext.com/carol-movie-delta-airlines/08/2016/

http://www.economist.com/blogs/gulliver/2017/01/sanitise-skies

olePigeon said:

Could it be that non-North American copies still have the original audio?

Unfortunately it doesn’t appear so:

http://www.dvdcompare.net/comparisons/film.php?fid=557