Trivia: Production was shut down for a year, to give Tom Hanks enough time to lose weight and grow out his "castaway" beard. During that time, director Robert Zemeckis used the same crew members to help film "What Lies Beneath."
Trivia: When the shots on the island were finished, the sound had to be completely redone, as the surf was too loud.
Trivia: Screenwriter William Broyles took survival courses and during that time a Wilson brand soccer ball washed up on shore - the inspiration for Wilson in the movie. The director Bob Zemeckis states in the feature voiceover that they changed it to a volley ball because "a soccer ball has all those black spots on it'.
Answer: No one knows what was in the package. I think Chuck doesn't open it in order to keep his sanity. The package is his only link to his life before being stranded, working for FedEx and making sure packages get delivered. He was determined to make sure it got delivered just as he was determined to survive and get back to civilization. Success in one meant success in the other. While Zemeckis has joked there was a waterproof satellite phone in it, the real answer from the script is, no joke, salsa verde. Its a care package with a note imploring Bettina's (the artist) husband (naked cowboy) to come back and spice up their life like the salsa.