The jeep Indy finds in the game has the number 1899 on it - his birth year. (So he's 48 here - and still in shape).
On the overhead map indicating Indy's approach to Teotihuacán, Mexico, one can view among other Central American and Caribbean countries designations for El Marrow, near the base of the Yucatan Peninsula, and Melee Island™, just south from the western edge of Cuba. These fictional locations figure prominently in earlier LucasArts games Grim Fandango and the Secret of Monkey Island, respectively.
(currently viewable at http://mixnmojo.com/galleries/gallery.php?gallery=123&image=1770 and http://www.scummbar.com/resources/articles/MonkeyIslandinIndy/images/indy3d_melee.jpg)
To further the Guybrush Threepwood "skin" mentioned below, use of the bazooka weapon while "dressed" as Guybrush will produce, instead of a rocketing bazooka shell, the explosive propulsion of a rubber chicken, as Monkey Island-ish Caribbean tropical steel drum music plays on.
(Determining whether or not the rubber chicken contains a pulley in its middle is left as an exercise for the reader.)
Due to declining sales of the Nintendo 64 at the end of its life cycle, the only way gamers could get ahold of this title were through two exclusives: Blockbuster Video had an exclusive for rental of the title, and for those who wished to purchase the game, this could only be done through ordering it from the Lucasarts website.
Indiana Jones is voiced in this game by Doug Lee who also voiced him in Indiana Jones and the Fate of Atlantis ( CD Talkie Version )
During the game, if you type "makemeapirate," you'll become a 3-dimensional Guybrush Threepwood!
Also, In the final level (the Aetherium, I believe it's called), if you wander around through the weightless passages, you'll eventually find the barbershop from The Curse of Monkey Island, in beautiful 3-D, with pictures on the walls of people ranging from Steven Spielberg to Max to Jar-Jar Binks (No, you can't blow up the picture of Jar-Jar).
In the german version of this game, Indy's dubbed by Wolfgang Pampel, Harrison Ford's official german voice known from the movies. This significantly adds to the atmosphere.