Did you know, that in the original game, Jak and Daxter the Precursor Legacy, the developers(Naughty Dog) created a special alphabet for the game, that they used to decorate ancient Precursor artifacts, such as the Precursor Orb?
Furthermore, in the second game, Jak II(with the subtitle Renegade in Europe), they hid a memorial to Jason Rubin(co-founder of Naughty Dog)'s dog, Morgan. Featuring messages such as "Morgan is still missed even after a year has passed" "Good dog" and "There will never be another".
And a smaller tidbit: In the original Crash Bandicoot,
the logo sequence for Naughty Dog features a cartoony portrait of Morgan.