Boam reworked the script to add the comedic bickering between Indy and Henry Jones Sr. (played by Sean Connery ), which became the heart of the film.
The final film was written by Jeffrey Boam , but several famous "drafts" by other writers helped shape the story: Indiana Jones y La Ultima Cruzada
This version introduced the Holy Grail as the central artifact and established the father-son dynamic. However, it was considered too serious and lacked the humor of the finished movie. Boam reworked the script to add the comedic
"The quest for the Holy Grail is not archaeology, it's a race against evil." Quotes - Indiana Jones and the Last Crusade (1989) - IMDb Indiana Jones y La Ultima Cruzada