I've just read the entire report.
From an LAEs point of view.
The certifying LAE says that he knew they were fitted and noticed them on his walk round but then forgot about them? What about the 'mandatory' open log book entry? Reading between the lines he didn't log it.
Also, there is an AD from Airbus requiring pitot covers to be removed before applying electrical power to the aircraft due to the possibility of the pitot probe heating switching on and melting the covers. (I can't find a reference for this so I don't know if it was issued before or after this event).
Placing a placard on the flight deck is also now mandated.
The practice of fitting gags and covers drawn from stores and not booking them out of stores is, sadly, all too common. Time constraints being the main driver. It needs addressing.
In this case it seems the covers were not even the correct type and had minimal streamers attached. For a station like Brisbane where the practice of fitting these covers is an everyday occurrence that is a shocking admission of poor standards from the operator. They should be kept on board and counted in for every Brisbane flight. They're not exactly expensive.
I won't comment on the crew actions as there are far more here qualified to do so.