Jack Nicholson's own experience in the hospital, just prior to filming, inspired some of the dialogue and acting for the movie. For example, the mirrored glasses seen in the movie were not originally in the script, but Nicholson, who obtained them while in the hospital, brought them to the set. Director Rob Reiner decided to include them in the film.
Morgan Freeman once said in an interview that Jack Nicholson was on his bucket list, and eventually got the chance of acting with him in this movie.
Kopi Luwak is indeed the most expensive coffee in the world, priced between $120 and $600 per pound. Its production is very slow due to its "animal stage". The beans come from coffee berries which have been eaten by, and passed through the digestive tract of, the Asian Palm Civet.