Mona Lisa is an alien lizard in this episode; in Teenage Mutant Ninja Turtles (1987) she was a mutant lizard.
Raphael christens Ik'thba with the title of Mona Lisa, a work of art that he calls a picture of the most beautiful woman in the world. This is a homage to Venus de Milo from Ninja Turtles: The Next Mutation (1997) who had an original birth-name but was re-christened with a name based on an acclaimed work of art.
This isn't the first animated cartoon episode to feature both Keith David and Michael Dorn. The two previously worked together on Disney's GARGOYLES--- Keith David played Goliath, and Michael Dorn played Coldstone.