The reason for the missing American items it is a British War Museum and Memorial. The reason for a British War Museum and Memorial is because the British liberated Bayeux, not Americans.
The empty flagpole I do not know what it represents, but as far as I can tell, it has always been empty. That particular display is a memorial to the Sherwood Rangers who were British. Canada was a part of the British Commonwealth at the time and fought with the British, which is the reason for the Canadian Flag.