The Shooting Star

Hergé has an animated cameo seven minutes in as blonde man in pajamas standing in the street.

At one point, Tintin observes the titular asteroid through a big telescope. It looks as though there was a giant spider on it but Tintin finds out that the spider was just crawling across the telescope's front lens. In reality, objects on the front lens are so far out of focus as to be invisible, causing at most some extra blur. However, as it turns out, this happens in a dream sequence where anything is possible.

Version of Die Abenteuer von Tim und Struppi: L'étoile mystérieuse (1959)