  In this document we address an error discovered in the ensemble generation
for our calculation of the $I=0$ $K\to\pi\pi$ amplitude (Phys. Rev. Lett. 115,
212001 (2015), arXiv:1505.07863) whereby the same random numbers were used for
the two independent quark flavors, resulting in small but measurable
correlations between gauge observables separated by 12 units in the
y-direction. We conclude that the effects of this error are negligible compared
to the overall errors on our calculation.
