S.S.
My 16-month-old son loves Handy Manny, Go Diego Go, Imagination Movers, Winnie the Pooh (we used lots of these while potty training). He would watch Handy Manny and Go Diego Go OVER AND OVER AND OVER and not be sick of it. He also likes Finding Nemo (fish movie, he calls it) and 101 Dalmations (Gog movie) and any of those simpler little kid Disney movies. I bought Blue's Clues but he didn't seem too interested any more.
My son also likes to color and draw. I give him 1 or 2 crayons and remind him not to put them in his mouth and he will color his Handy Manny and Pooh coloring books (I picked them up at the dollar store...also used them for potty training times). I also just bought him the Crayola Color Wonder crayons because he was starting to color on the actual potty and I thought they would help that and they are actually pretty cool, though I don't like that the colors aren't exactly right (red is more maroon), but they might give him something else to do...they also have "finger paint" and "markers" as well! Pretty cool! Even just a plain notebook and a pencil or pen works well too.
Oh, and maybe pick up a travel size Doodle Pad (those are those ones with the pen attached with a magnet on the end and they draw and then they can erase it and start over. My son got one for Christmas from my parents and HE LOVES IT! You can find them at Target or Walmart in the toy section. There are bigger ones that come with other magnets, but those might be hard on the plane. I think they also have a travel-sized Aqua Doodle, which might be cool. The ages are a little older on the Aqua Doodle, Doodle Pad and Color Magic, but with supervision, they should be fine!!! Hope something helps!