  We clarify that a result recently stated by Kaiser is contained in a theorem
of Buchert and Ehlers that is widely known for its main result: that there is
no global kinematical backreaction in Newtonian cosmology. Kaiser cites this
paper, re-derives parts of the theorem, but incompletely restates its content.
He makes further claims, which cannot be proven beyond the limited context of
Newtonian cosmology. We also discuss recent papers of R\'acz et al. and Roukema
who claim the existence of global backreaction within the Newtonian framework.
