Created in 1989, A Grand Day Out was the first film created by Nick Park. Even though it was the start of the Wallace and Gromit series, it still has some cool hidden details, nods to other films, and foreshadowing of Aardman's future films.
You can read the original blog post here:
www.blogblowfish.com/2015/10/02/easter-eggs-in-wallace-and-gromit-a-grand-day-out/