Ryan Reynolds plays Elisabeth Harnois's father despite being less than three years older than her (945 days to be specific). Emily Mortimer, who plays Elisabeth Harnois's mother, is less than eight years older than her in real life.
Ty Olsson (Evil Ferryman) and Christine Chatelain (Tracey) also guest starred on the long running CW series Supernatural as vampires Benny LaFitte and Jenny respectively.
Ty Olsson and Ryan Reynolds's starred in the movie Just Friends together in 2005.
Alessandro Juliani (Ken) and Ty Olson (Evil Ferryman) were both in Battlestar Galactica (2004) together as Lt. Felix Gaeta and Captain Aaron Kelly. They share no scenes in Chaos Theory but shared several in Battlestar Galactica.