Oh, wow, here is an interesting bug in the original Adventure game, purportedly whose discovery was not published until relatively recently. What is it? It is peculiarities with how the capacity of containers are counted in your inventory. A quirk in the rules required some exceptional condition handling code to be copied and pasted throughout many different other locations in the code, but some locations were missed. The result? You can effectively increase your inventory capacity by one.
20200206/https://quuxplusone.github.io/blog/2020/02/06/water-bottle-bug/