I was wondering how they were going to get a great white shark in the swimming pool and then once that was done, how they would train it do turn around after 50m. Then I realized how ridiculous I was being.

Sharks can turn pretty quickly and since they were under water, he could turn without interfering with Phelps. Duh...

It's on right now and I was only able to take about 5 minutes of it :P