Perforations
Despite the prestige attached to this stamp, surprisingly not all examples that were sent out were nicely perforated. Some had the perforations right up to the edge of the design, while there are some with extra perforation lines through the stamp. This is possibly explained by the limited number of sheets available where virtually every stamp that got perforated contributed to the 500 to be sent out. There was even one report of a stamp that was Bath perforated on two sides and Wincanton perforated on the other. This is very odd unless a sheet was one of the last to be perforated at the Museum and the Wincanton perforator was about to be used, when it was found that one line of perforating had been missed, and so corrected. While no image was supplied the owner stated it had been checked with a perforation gauge.
While perforating the sheets with a diagonal line as well as horizontals and verticals was going to be trickier, the slight mistakes did have some profound results. Here is one triangle with the bottom perforations touching the stamp design. With the other two perforations being reasonable correct, a stamp much smaller results.

This makes it much harder to display the stamps in mounts in an album, and have them looking neat and tidy. They should not really have sent out examples of such a flagship stamp with such low production quality.

Ephemera
The Blue Triangle has featured on a Year of the Prawn AMPO proof sheet, on the Discworld Stamp Collection collector`s cards (split over two cards), and as a fridge magnet.

Imperforates
Some inkjet printed versions have appeared on post sent to collectors from a certain address in Norfolk. They are slightly smaller than the real version and are straight cut (unperforated). There is no guarantee that the colour on these would not start to fade over time, but they would be a great addition to any collection - mine in particular! The other stamps here are also very tasty.

In 2009, after some of these sold on eBay as prototypes, Colin Edwards wrote These are not prototypes of any sort. They were sent out after our appearance at Stampex when I cut up the test version of the pop-up Display panel I presented there to Bernard, and sold the component artwork on eBay to cover its production costs. Buyers received the inkjet printed stamps as an extra because I thought everyone involved had spent far too much and should receive a bonus! However they are NOT prototypes, and because they are printed on standard Epson paper the inks will fade with time and the paper will soon yellow. I would define a prototype as an early work in progress produced for us as a test sheet, or for Terry or Bernard's approval and therefore subject to change. These artworks are nothing of the kind and apart from the size difference (done to differentiate them from the correct stamp) they are identical to the final printed stamps.
 

Cut out post box kit
An nice addition to the AMPO accessories was the Cut-out Victorian style post box which coincided with the Post Box commemorative stamp. In the margin of the card are pictures of the Blue Triangle and its successor, the $5 Purple Triangle. Both have one of the postboxes added to the artwork. On the Blue Triangle it is positioned over the assassin on the bridge.