well.. it is an old plane. I think Disney is using unmarked Learjets (other than registration) and regular Passenger planes now
I know other than N234MM, they also owned N2MM... but that's it..
(yes.. I love airplanes...)
*edit*
here's the aircraft registration info.. apparently, it's still Airworthy:
N-number : N234MM
Aircraft Serial Number : 121
Aircraft Manufacturer : GRUMMAN
Model : G-159
Engine Manufacturer : ROLL-ROYCE
Model : DART 529
Aircraft Year : 1963
Owner Name : WALT DISNEY WORLD CO
Owner Address : PO BOX 40
LAKE BUENA VISTA, FL, 32830
Registration Date : 13-May-1986
Airworthiness Certificate Type : Standard
Approved Operations : Transport