Tom Ellis uses an American accent to portray his character but his real accent is Welsh.
In the pilot, hard-drinking all-around addict Rush Tom Ellis claims he doesn't need as much sleep as normal humans. When Eve reminds him he is human nevertheless, he facetiously implies he isn't. The following year Ellis was cast in Lucifer (2016) as the Devil, who can function on very little sleep and has a supernatural tolerance for drugs and drink.
Each episode is named after a song, aside from the pilot.
According to lead actor Tom Ellis, the "cocaine" that Rush snorts is composed of lactose powder. This is a common powder that is safe to inhale in small amounts and is found in dry powder inhalers such as those used to treat asthma.
Prior to getting the part of Rush, Tom Ellis was doing a play in London called The Lyons where he played an American and that's how he started developing his American accent.