Barry and Harry use their new device to close one of the breaches in episode 2x12 “Fast Lane”.
Barry catches up with Eobard Thawne in a warehouse and almost kills him before being talked down in episode 2x11 “The Reverse-Flash Returns”.
Mercury Labs Research Facility
Eobard Thawne takes Dr. McGee to a Mercury Labs facility to build him a speed cannon so he can return to the future in episode 2x11 “The Reverse-Flash Returns”.
Tarpit kills one of the people who tried to kill him in episode 2x12 “Fast Lane”.