Trivia: The Pizza Planet truck from "Toy Story" passes by Miguel's house near the beginning of the film. Also in the marketplace, a small Nemo doll is on a table and dolls of Mike Wazowski and Woody are hanging from a stall.
Trivia: Director Lee Unkrich is a fan of the movie The Shining - in Frida's place twins in blue dresses can be seen.
Trivia: On the dead altar a clown fish can be seen, a reference to Finding Nemo.
Trivia: The number A-113 can be seen in Ernesto de la Cruz's album, often referenced by animators.
Answer: It is never really explained in the movie, but we could assume that whenever someone dies they keep whatever items they had on them. Hector may have had the photo on his person when he died.