Easter egg: On the film disc (disc 1) of the Theatrical Version, in the language selection menu there is a THX logo somewhere. Highlight it using the arrows on your remote, then enter the number 1138 while you have it highlighted (may vary on different DVD players, on mine I have to push a little 10 button, then 1 1 3 8, which makes 1138). You will then be treated to a sequence of bloopers from the film.
Easter egg: Insert Disc 2, the special features. Go to Dex's Diner. You will hear him greet you, then he freezes and the menu pops up. In the kitchen behind Dex, you will see a purple poster. Highlight it and click it. It will pop up different hand-drawn posters advertising Attack of the Clones.
Easter egg: When the disk is starting up and it gets to the attention scene press 1, 2 or 3 to get a different main menu.
Chosen answer: Because he dropped it earlier while chasing Zam Wesell on Coruscant. Obi-Wan caught it that time and scolded him for losing it.