The crate was nailed shut and filled with dirt or a dirt-like substance. Buried in the dirt were two zombie arms, a street sign, and a padlock. Father down was a large coffin, also nailed shut. The interior of the lid of the coffin is scratched as if the zombie was clawing at it, and also playing a game of hangman. Inside the coffin was a zombie. The tag and scroll give care advice for the zombie, which is poseable.
(Pro tip, I used a tiny flat head screwdriver as a crowbar, and a toothbrush to clean off the coffin.)
Here's a new video showing how swappable faces are used to animate the characters:
And here's a charming video introducing the artists at Laika who made the movie (sort of an "it gets better" theme):