The license plate on the truck near the end of the movie reads A113, a popular Easter egg that can be found in most Pixar movies.
A113 is a nod to the CalArts first-year graphic design and character animation classroom where many artists and animators at Pixar studied. You can read more about it here.
The registration number for the boat that grabs Dory outside the Marine Life Institute is PA1200. That's short for Pixar's address: 1200 Park Avenue.
Let's see if you can spot this one. There's a character from "Inside Out" — another Pixar movie — hiding out in this group of children.
She had trouble adjusting after her family moved to San Francisco. It looks like she's doing a bit better now.
Bonus: You can spot the dentist's niece Darla from "Finding Nemo" in the background when Dory first arrives at the Marine Life Institute.
Here's a close up of the image.
Pixar released an image with the Easter egg in it a while back. You can read more about it here from when we first wrote about it in June.