When King Shark gets its arm cut off, Snart remarks "Ouch, been there" he's referring to the first season of Legends of Tomorrow episode Left Behind (2016) when he froze and smashed his hand to escape being handcuffed.
Infantino Street is a homage to Carmine Infantino, the comic book artist who co-created the second Flash Barry Allen with Robert Kanigher. The character made his first appearance in Showcase #4 (October 1956).
When Barry and Snart are investigating the underground section of the A.R.G.U.S. building, they discover a door marked "Cheetah." This is a reference to the comic book supervillain the Cheetah, a major adversary of Wonder Woman. The first Cheetah, Priscilla Rich, was introduced in Wonder Woman #6 (October 1943). The third and current Cheetah, Barbara Ann Minerva, made her first appearance in Wonder Woman Volume 2 #7 (August 1987).
Snart offers to put a good word in with his sister for Cisco, alluding to Cisco's past flirtations with Lisa Snart, aka the Golden Glider.