It would be interesting to find out what the BoC has to say about this. If indeed such a huge error slipped through their single note inspection process then I it could be something of interest to them.
A number of years ago I had found 2 wet trap errors with a cancellation mark on the note each in one of two consecutive BOC bricks
I sent the information, with numerous photos of the notes to the BOC and later received an email stating that the error is due to excessive ink on the plates not being properly cleaned and the notes are normally pulled by QC, but were obviously missed...(I assume some were removed since replacement snrs were the shoulder notes to this error in each brick) which were later confirmed as replacements.
They also suggested I send a note in for inspection by quality control and they could hopefully explain exactly what happened. A big mistake!!!!!!!!!!!!!!!!!!
Along with the note, a complete explanation of where the note was in the brick and what was shouldering the note, as well as a self addressed return Xpresspost envelope with cardboard and sleeves for the notes to be safely returned after inspection.... about 2 months later I received a BOC cheque for $15.00 for the three notes. The only explanation was that the "note was not to be released into circulation and will be destroyed it was inadvertently bypassed by QC no mention of the other 2 notes"
First and last time I will ever send notes to the BOC even when I was told the notes would be returned after inspection.......
As for this note, it has been seen by a number of individuals for inspection, in particular a very well known and respected error collector..As for how the error occurred I have no idea as I do not know the exact process of making the polymer note...all I can say is that the brick was a new sealed brick that was opened by me...there was no other person that had access to the brick and it was packaged like all the other bricks that I have been receiving in the polymer series.
As for being of interest to the BOC...I think they have said it enough times before...they print banknotes not art...I doubt they could care less

FRIEDSQUID