Three Commermoratives were issued in 1933.

The first One was issued to commemorate the Universal Postal Union Executive Committee meeting in Ottawa that year
 

202-01 Roessler

202-02 Eagle Cover Service

202-03 Dyer: type 1

202-04 Dyer: type 2

The Ralph Dyer covers above are to my knowledge, the only ones in existence for that issue.

An Overprint on the 20 Cents stamp from the "scroll" Series was issued for the the Worlds Grain Exhibition and Conference in Regina

A number of stamped cachets are known for this issue. This is the only printed cachet actually mentioning the conference
A number of stamped cachets complementing commercial envelopes can be found. Some even have a metallic seal applied to the envelope.
 
 
 

On August 18 1933, a commemorative stamp was issued after the 100th anniversary of the Transatlantic crossing of the Royal Williams entirely by Steam.

Some slight variations in the messages on this cover (both sides shown) exist.
 
 

Other known cachets for this issue: