When Razor and Sally are talking in front of his house (across the street from railroad tracks) the background alternates from no trains to a stopped train to a moving train throughout the conversation.
When Razor and the Kid are in the studio to record for the video game, the kid initiates a fight by lightly pushing/bumping Razor's head with his fist when people start recording it with their phones. However, a little later when the video goes viral on YouTube and Dante is showing it to them on his phone, it's obvious another take was used for the part in which The Kid initiates the fight.
The first time you see the viral footage shown of Razor and the Kid fighting for the video game is from the actual phone used. You can clearly see the crew filming the scene including cameraman and boom guy.