The paint job really. I think that whale on the side did tons to get kids and infrequent flyers excited about their flight, the airline, and aviation in general. People who would normally have no love for flying identify with that sort of fun and whimsy.

For the record, while there may be some inaccuracies or bias to the film, I think it's core message is sound. We see in those whales something that reminds us of ourselves. Highly intelligent and social with very developed family groups. Why is our response to keep them contained instead of wild?