Ratchet & Clank:

When You Are In The Camera 4B You Will See A Poster With Ratchet & Clank Face

Abe The Mudokon:

When You Complete All The Nights You Have The Costume Night Mode When You Press Some Of The Challenges You Will See Abe In The Left Corner But He Will Not Kill You

Jax And Dexter:

When You Are Turning The Camera Off And On You Will See Jax And Dexter In Your Room

Comment If You Want To See More Characters As A Easter Egg