Dan pronounces "coup de grâce" as "koo de GRAH." The S sound at the end is not silent, so it is correctly pronounced "koo de GRAHSS."
After a student from Professor Crowley's class says that they worship him, he sneers, "Sure, like a school of piranha worships a hippopotamus?" Piranha live in South America and hippos are native to Africa, so those two species would never encounter each other.