At the end of Series 2, Ricky asks Karl if there's anything he didn't do that he might have, had he done it again. He says that he would have quite liked to do some karaoke in Japan, singing some Chas And Dave. Cut to Karl recording There Ain't No Pleasing You, with Chas And Dave. It's impossible not to smile at just how happy he is.
After meeting the transgenders in Bangkok, Karl muses about how he'd react if he found out Suzanne was 'actually a bloke' and concludes perhaps he wouldn't mind. Think about that for a moment, Karl is so fond of his girlfriend he wouldn't mind if she turned out to be a man. Awwww... (still, Karl being Karl he would expect her/him to pull her/his weight a bit more and carry heavy shopping with him).
In season 3 Karl and Warwick Davis had a genuine heart to heart moment when Warwick was having difficulties climbing the stairs of Mount Emei and after their moment Warwick pushes through and reaches the top of the mountain. Just seeing how the usually pessimistic and grumpy Karl having a You Are Better Than You Think You Are talk with Warwick just warms the heart even though they still snipe each other and argue.
In season 2 when Karl is in Japan, he experiences the Japanese tea ceremony. Although he makes a little joke at first, he ends up liking it because it turns the drinking of tea into an event, and he is able to connect with the other participants over their love of tea, even though many of them couldn't speak English.