- Costas was nominated in 1995 and 1996 for a SAG Award for Outstanding Performance by an Ensemble in a Drama Series for Picket Fences.
- Costas' parents are named Louise and John.
- When Costas guest starred (with his brother) on Charmed
(episode: Saving Private Leo), he was reunited with his Picket Fences co-star, Holly Marie Combs.
- Costas was maried to actress Talisa Soto from 1997 to 2000.
- Costas appeared in a Playboy pictorial in February 1995.
- Costas moved to Greece to play soccer when he was only 16 years old. He played midfielder for the team Panathiakos.
- The movie Just Desserts on the Hallmark channel reunites Costas with his Picket Fences costar, Lauren Holly. The romantic comedy also features a cameo by celebrity chef Wolfgang Puck.
- Wedding Belles reunites Costas with producer David E. Kelly, who was also behind Costas' role in Picket Fences.
- Costas is 5'11".
- In 1991, People magazine named Costas as one of its 50 Most Beautiful people. In 2000, People named him one of their Awesome Aussies.
- The Mandylor name is a variation of Costas' mother's maiden name, Mandylaris.
- Costas' brother, Louis Mandylor, is also an actor.
- While starring in Players, Costas appeared in 2 public service announcements for NBC's The More You Know. His topics were teen pregnancy and substance abuse.
- Costas: Life teaches you lessons. You either pay attention to them or you don't. I really feel like I'm standing my ground now and taking chances. I'm doing things I want to do, not what others want me to do. That means I'm owning myself.
- Costas: There are only twenty million people in Australia. Where I come from, Melbourne, you can't get away from family. Here you can escape from it. At home, you can't. You'll see a cousin down one street. Turn a corner and you'll spot an uncle. People stay close together without even trying.
- Costas: Sometimes in movies, a nice face can't act, I don't want to have that problem. Hey, I'll blacken my tooth, pull out my eye, anything to get a decent role.
- Costas: (About what's not sexy)
Mind games and flashy cars.
(about what is sexy)
A man and a woman having hunger for each other.
