Normally a game will end when one player reaches the ammount of points he is supposed to get. However, if you have a game of 3-4 players, and your person has 2 kills(you have to get 3 to win), if that person kills two people at once, it skips the 3 and goes to 4, thus messing up the counter, and the game will never end untill you reset the game.
You can view two different pieces of artwork for beating Venom on expert mode. The artwork you see depends whether you beat Venom on the easy path or hard.
Certain characters will appear to assist you, depending on the order that you beat the levels