Unlock Venom and new Green Goblin
Venom and new Green Goblin (from the movie) can be unlocked by entering the following codes using the D-Pad when standing in the Helicarrier in between levels. You should hear a tone indicating you entered the code correctly and they will then be selectable from the sidekick select console:
[Left], [Down], [Right], [Right], [Down], [Left] - New Green Goblin
[Left], [Left], [Right], [Up], [Down], [Down] - Venom
[Up], [Up], [Down], [Down], [Left], [Right] - 5000 upgrade tokens
[Right], [Right], [Right], [Up], [Down], [Left] - Sandman