  We broadly explore the effects of systematic errors on reverberation mapping
lag uncertainty estimates from {\tt JAVELIN} and the interpolated
cross-correlation function (ICCF) method. We focus on simulated lightcurves
from random realizations of the lightcurves of five intensively monitored AGNs.
Both methods generally work well even in the presence of systematic errors,
although {\tt JAVELIN} generally provides better error estimates. Poorly
estimated lightcurve uncertainties have less effect on the ICCF method because,
unlike {\tt JAVELIN}, it does not explicitly assume Gaussian statistics.
Neither method is sensitive to changes in the stochastic process driving the
continuum or the transfer function relating the line lightcurve to the
continuum. The only systematic error we considered that causes significant
problems is if the line lightcurve is not a smoothed and shifted version of the
continuum lightcurve but instead contains some additional sources of
variability.
