Audio problem: After Kate shoots an arrow at the mafia guys, she says "told ya." Then we hear Clint/Hawkeye say "yeah", except he's on camera and his mouth doesn't move, he doesn't even change his facial expression.
Never Meet Your Heroes - S1-E1
Continuity mistake: When the Avengers appear on the catwalk during the musical, Hawkeye is next to Cap but in the next shot he's now next to Hulk and then back by Cap in the following shot.
More trivia for Hawkeye