In case anyone's interested, here's the relevant Canadian regulations.
They claim I busted (4).

Requirement to File a Flight Plan or a Flight Itinerary

602.73 (1) Subject to subsection (3), no pilot-in-command shall operate
an aircraft in IFR flight unless an IFR flight plan has been filed.

(2) No pilot-in-command shall operate an aircraft in VFR flight unless
a VFR flight plan or a VFR flight itinerary has been filed, except
where the flight is conducted within 25 nautical miles of the departure
aerodrome.

(3) A pilot-in-command may file an IFR flight itinerary instead of an
IFR flight plan where

(a) the flight is conducted in part or in whole outside controlled
airspace; or

(b) facilities are inadequate to permit the communication of flight
plan information to an air traffic control unit, a flight service
station or a community aerodrome radio station.

(4) Notwithstanding anything in this Division, no pilot-in-command
shall, unless a flight plan has been filed, operate an aircraft between
Canada and a foreign state.