I had similar experience couple of weeks ago when they rerouted me.
Original flight was YUL-YYZ-FLL.. YYZ Aircraft inbound YUL outbound to YYZ was significantly delayed because of engine malfunction.. So they rebooked me to a non-stop flight YUL-FLL but my luggage was tagged YUL-YYZ-FLL so it went to YYZ instead.
(I was also puzzled that the luggage flew without the original passenger on board)

During boarding they said I won't have my checked in luggage when I arrive so I should report to the Baggage Office for claims, which I did.

When I called the Baggage Department Number they said you can claim up to $100 for all the purchases needed in lieu for the delayed check in luggage.

And also if you purchase the ticket using a travel reward card, you might be covered with the baggage insurance. I used my CIBC Credit Card and I was able to claim up to $500.