During the Credits
Besides an image of Ratchet & Clank in the background, there are no other extras during the credits of Ratchet & Clank: All 4 One.
After the Credits
There is an extra scene after the credits of Rachet & Clank: All 4 One, check out more details and spoilers below.
The short extra scene after the credits shows Nefarious in his ship and looking at a polaroid picture of him with Rachet, Clank, and Captain Qwark back when they were all friends.