MacKellar attracted some controversy over his handling of an incident involving the improper importation of a colour television set.

In 1982, a ministerial staffer submitted an incorrect customs declaration form when arranging for the set to be imported.

MacKellar resigned from Parliament on 18 February 1994, causing a by-election that was subsequently won by future Prime Minister Tony Abbott.

MacKellar also served as the president of the Melbourne-based National Ageing Research Institute.

His daughter Maggie was the subject of an episode of ABC TV's Australian Story.