While treating a patient hiding money in his pants, a paint bomb goes off, splashing Susan Lewis across her chest and her face shield. She's later seen trying to clean the green paint off her lab coat despite her wearing a medical gown when the canister blew up.
Ray claims that "payaso" means "little clown" in English. It merely means "clown." To mean little clown, one would say in Spanish "payasito."
When Nurse Hathaway rides along with the ambulance crew, she is wearing a flimsy, almost sleeveless shirt, which would offer no protection against any hazards that one might face while running ambulance calls. Nurse Hathaway is too experienced to not wear a better shirt.