Katrina Law and Johnathon Schaech both starred in an Arrowverse show, Law was in season three of Arrow (2012) and Schaech was in a few episodes of DC's Legends of Tomorrow (2016).
The title "Year 2" confused some people who thought this was a sequel. But the title refers to the year after (i.e. second year) an event that leads to people becoming werewolves.
Katrina Law is a series regular of NCIS (2003) and James Kyson was in an episode of NCIS: Los Angeles (2009). They also appeared in different episodes of Hawaii Five-0 (2010).