A few thoughts:
Officers may have had Regimental Numbers if the were originally enrolled as Non-commissioned pers.
VAC page @ http://www.collectionscanada.ca/archivianet/02015203_e.html states:
Regimental Numbers
From 1914 until 1917, the Canadian Expeditionary Force was composed of men who had volunteered to fight. Able-bodied men were actively encouraged to enlist by Recruiting Officers who worked throughout the country. In larger urban areas, Recruiting Officers often worked from stationary recruiting centres, while in rural areas they travelled to many towns, counties or, in the west, large sections of provinces. Individual Recruiting Officers were told to recruit a specific number of men for a specific unit.
Before setting out to recruit their men, Recruiting Officers were assigned a block of regimental numbers. They assigned one regimental number to each man that enlisted. The Regimental Numbers list of the Canadian Expeditionary Force matches the military unit assigned to each block of regimental numbers. Therefore, the Regimental Number list can be used to identify the unit in which a man initially served.
This will not apply to men who were conscripted into the military in 1917. After that date regimental numbers were given to men in the order in which they were called up for service.
Officers who attended military college could be referenced by their college number, more info at:
http://www.rmcclub.ca/AboutUs/CollegeNumbers.htm
Did commissioning scrolls ever or originally have serial numbers?
The CF used to annually publish an Officers List with significant identifying data. Final thought - officers were identified by rank and Regiment and were seen as a member of the Officers Corps.