This is a really neat spot the difference puzzle. A few things: the eyes are wrong on the green slime ghost, the desk is missing drawers, there's no beta text on the logo, the pillow is missing, there's no detailing on the cake, no message from dad, and no detailing on the poster. Also the doorknob is far smaller than it should be. I think that should be it, aside from the obvious one of this being a still image as opposed to a gif