Disney doesn't use any actual strobe lights, but there might be random flashes of bright light in different shows. The major one in Nemo would be when the sharks and boat blow up.
This youtube video shows the shark part at the beginning. The 'blow up' part is at about 3:26.
If you are concerned about lights, there is information in the "Epilepsy" thread that is linked in post #3 of the disABILITIES FAQs thread. That thread is stuck near the top of this board or you can use a link in my signature to get there.