...it will kill your cart and ability to check out (at least on Firefox 60.2 and Chromium 60.9). I was buying casters as their annual sale just started, and was browsing through all sale/clearance items and saw the knife. I knew it was an error, and once I added it to my cart, I couldn't get to my cart anymore or check out. I had to clear cookies and restart the browser to get a clean cart and then reorder items.
It took me longer to write this post than go through the process, so maybe I save a few other people the aggravation from excess curiosity/ "deal" seeking.
P.S. - I called it into Customer Care already.