What drugs or other things besides methodone would cause a person to have a positive methodone urine test?

Nyquil Nighttime Cold Medicine will test positive for Methadone up to two days
Adderall - false positive for meth in urine tests
Combivent inhaler - false positive for meth in urine tests
Concerta - false positive for meth in urine tests

Although most of those were for Methamphetamine

Any opiates might? Methadone is a synthetic opiate, so it's hard to say I am surprised that they would test for this. Usually they just test for opiates, in general.