  We make a number of comments regarding modeling degeneracies in strong
lensing measurements of the Hubble parameter $H_0$. The first point concerns
the impact of weak lensing associated with different segments of the line of
sight. We show that external convergence terms associated with the lens-source
and observer-lens segments need to be included in cosmographic modeling, in
addition to the usual observer-source term, to avoid systematic bias in the
inferred value of $H_0$. Specifically, we show how an incomplete account of
some line of sight terms biases stellar kinematics as well as ray tracing
simulation methods to alleviate the mass sheet degeneracy. The second point
concerns the use of imaging data for multiple strongly-lensed sources in a
given system. We show that the mass sheet degeneracy is not fully resolved by
the availability of multiple sources: some degeneracy remains because of
differential external convergence between the different sources. Similarly,
differential external convergence also complicates the use of multiple sources
in addressing the approximate mass sheet degeneracy associated with a local
("internal") core component in lens galaxies. This internal-external degeneracy
is amplified by the non-monotonicity of the angular diameter distance as a
function of redshift. For a rough assessment of the weak lensing effects, we
provide estimates of external convergence using the nonlinear matter power
spectrum, paying attention to non-equal time correlators.
