To familiarize himself with Bauby's sheltered existence, director Julian Schnabel made the movie in the same hospital where Bauby was treated, meeting many of the orderlies who had treated him. He also shot scenes on the same balcony where Bauby relaxed, and on the same nearby beach his family took him to.
The script was originally in English and Johnny Depp was cast to play Jean-Dominique Bauby. He dropped out because it conflicted with filming of "Pirates of the Caribbean: At World's End." Gary Oldman was also in consideration. But eventually, director Julian Schnabel convinced the studio (Pathé, a French studio founded in Paris) to change the language to French to stay true to Bauby's life and story.
In the movie, Bauby is visited by a friend named Roussin (Jean-Paul K in the book), about whom Bauby feels guilty as his friend was captured and held hostage in Beirut, Lebanon after Bauby gives Roussin his airline seat. In reality, although Jean-Paul K was indeed held hostage in Beirut, it was not due to having been given Bauby's seat. In the book, Bauby expresses guilt at never having contacted his friend upon his release, and there is no mention that the two met up again after Bauby's stroke.
The trivia item below may give away important plot points.
After the making of the film, it was widely confirmed that in actuality it was the girlfriend who was steadfastly by John-Dominique's side after his stroke, and not the mother of his children. It is unknown why these roles were reversed in the making of the film, but by all accounts his girlfriend helped with the book and in whose arms Bauby died, while the mother of his children was in the U.S. with her boyfriend when he passed.