A few things I've noticed:
* The gang in green is possibly now known as The Hills - check out the graffiti higher on the wall where it says "Grove St."
* The man being punched by Michael at the car dealership may be Franklin's Armenian employer.
* The scene where three bikes are being chased by police is more than likely a continuation of the jewellery store heist mission, as all three men on bikes are wearing what appears to be BugStars uniforms. Oddly enough, Michael and an unknown male are also observed in this sequence, but they are in a truck, which they ram into one of the police cars.
* The trio are seen robbing a jewellery store in clothing almost identical to that worn in the GTA IV mission "Three Leaf Clover".
* Trevor has a strange way of treating people who appear to be his friends.