When Iris asks Flash his real name, he replies, 'You mean, like Ralph?'. This is a nod to a scene in Superman (1978) when Lois first meets Superman. She asks if he has a first name. Superman replies, 'You mean, like Ralph, or something?'
Roy G. Bivolo is a comic book character who made his debut in Superboy #84 (Oct 1960). Unlike the show, the character in the comics is called Rainbow Raider (briefly mentioned by Caitlyn towards end of show). He was a failed artist due to his color blindness who turned to stealing art. His father gave him a special set of glasses that allows him to use light to make physical objects and to alter peoples emotions.
The villain, Roy G. Bivolo, uses colors to manipulate people. "Roy G Biv" is a common mnemonic for the order of the colors of a rainbow; Red, Orange, Yellow, Green, Blue, Indigo and Violet.
In the opening scenes, a board reads 'Made possible by Palmer Technologies.' Palmer Technologies is the company of DC Comics character Ray Palmer (The Atom) who appears in Arrow (2012). This is a foreshadowing of the crossover with Arrow.
The idea Caitlin and Felicity have about certain colors giving off certain emotions is a nod to the Lantern Corps and their colors being associated with emotions. (It's also based somewhat in fact.)
In the color spectrum based on the DC Universe, blue is Hope, green is Will, indigo is Compassion, red is Rage, and violet is Love.
In the color spectrum based on the DC Universe, blue is Hope, green is Will, indigo is Compassion, red is Rage, and violet is Love.