What are some of the hidden easter eggs in the nightmare before christmas?

The only verified information in the supplied reference is a list of characters that appear in the 1993 film and its related video games. It does not include any references to Easter eggs, hidden details, or behind‑the‑scenes trivia. Because the source contains no mention of Easter eggs, it cannot be confirmed that any exist based solely on this evidence. Users looking for Easter egg information may need to consult additional sources such as interviews, fan wikis, or official commentary. Until such evidence is available, the question about hidden Easter eggs remains unanswered in the context of the provided data.