Not exactly an embossing error, but certainly an embossing oddity! I found this common aqua B beehive in Texas many years ago and noticed a reverse incuse ampersand (&) just below and to the right of the embossed B. The size is identical to the ampersand on my CD 117. Apparently a CD 117 bumped into this piece while it was still hot and pliable. If there was ever any doubt that the ampersand (&) CD 117s were made by Brookfield, here's proof positive that they were!

There is also [id=259065528; detailed view] of this compared to a standard & from a Windows font.