CO had Flight 3 LAXHNL which was an homage to Airport (1970); if you recall CO3 was heard in the opening scene of Airport when its announced "attention, attention please. Continental Airlines announces the departure of flight 3 for Los Angeles and Honolulu"

What gets confusing though is when they reuse flight numbers on roundtrips, which is understandable because they only have 9999 combinations with 4 digits. I've seen ORDSTL and STLORD operate with the same flight number.