"Have the adventure of your life keeping up with the Joneses."
Indiana Jones and the Last Crusade - Easter Eggs & Hidden Details
Easter Eggs
In the catacombs beneath the Venetian library, an ancient carving on the wall depicts the Ark of the Covenant from 'Raiders of the Lost Ark'.
When Elsa points to a carving and asks about it, Indy briefly identifies it as the Ark of the Covenant. This is a direct visual callback to the artifact from the first film in the series, connecting the adventures.
During a scene in Walter Donovan's apartment, the 'Imperial March' (Darth Vader's theme) from 'Star Wars' can be faintly heard being played on a piano in the background.
This is a subtle nod to George Lucas's other major franchise. Julian Glover, who plays Donovan, also appeared in 'The Empire Strikes Back' as General Veers, adding another layer to the reference.
When Indy tells his class about the difference between archaeology and philosophy, he directs them to 'Dr. Tyree's' class down the hall.
This is a personal tribute from Harrison Ford to his real-life college philosophy mentor, Dr. William E. Tyree, from Ripon College.
On the ship at the beginning of the film, barrels marked 'Carboneto' are visible.
This is believed to be a subtle reference to 'Carbonite,' the substance Han Solo was frozen in during 'The Empire Strikes Back,' linking the two Harrison Ford characters.