foolmoron Oh, nice! 🙂
I'm afraid that if I did add this functionality, it would probably take a couple of months to implement and release.
You could try screenshotting or physically printing some vocab sheets for the trip.
For what it's worth, though, in my experience, probably the best way to kill time on an international flight is to bring earplugs, a sleep mask, and a coat and sleep, and also to download a bunch of phone games that work offline.
My recommendations for offline phone games:
- Rogue Slime
- Crossy Road
- Dungeon Cards
- Going Balls
- Neon Wings
- Tricky Castle (Can't remember if this one works offline, but it should)
(Some games might require opening them after they're downloaded so that you can log in, and then they should work offline)
Have fun! :D