Kate's fall into the canal
It was well known that the canals of Venice were terribly polluted. Before doing the scene where she fell into the canal, she covered herself with lotion, and put antiseptic cream on a small cut in her finger. Immediately afterwards, she bathed and gargled with antiseptic mouthwash. However, she didn't think to flush her eyes out, and the next morning her eyes were red. It turned out to be a staph infection that gave her trouble for almost the rest of her life.
I have heard that proper sewers have been constructed in Venice since then, but I don't know if the canals are any less polluted.