A group of school children are taking a tour of S.T.A.R. Labs when Harrison Wells shows up in episode 2x02 "Flash of Two Worlds". Wells is giving a press conference when he is interrupted by The Flash in episode 2x05 "The Darkness and the Light". Barry and Cisco marvel at Earth-2 in episode 2x13 "Welcome to Earth-2". Appears in 1 more episode.
The Earth-2 version of Barry talks to the police about the Zoom problem in episode 2x13 "Welcome to Earth-2".
H.R. approaches Tracy Brand at Jitters to keep an eye on her and talks about her research into the Speed Force in episode 3x20 "I Know Who You Are".
The new mayor is giving a press conference for the new 'meta-human proof' Kord Industries building when the entire skyscraper disappears in episode 4x12 "Honey, I Shrunk Team Flash".