Was at one point titled Ratchet & Clank: Four Play which can be seen on some concept art.
When Dr. Nefarious reanimates the Z'Grute from cyrosleep, he cries out "It's Alive! It's Alive!" while laughing maniacally, similarly to Dr. Frankenstein (Colin Clive) cries out the infamous line in the 1930 horror classic "Frankenstien".