  We discuss a recently presented boosted Kerr black hole solution which had
already been used by other authors. This boosted metric is based on wrong
assumptions regarding asymptotic inertial observers and moreover the performed
boost is not a proper Lorentz transformation. This note aims to clarify some of
the issues when boosting black holes and the necessary care in order to
interpret them. As it is wrongly claimed that the presented boosted Kerr metric
is of Bondi-Sachs type, we recall out some of the necessary requirements and
difficulties, when the casting the Kerr metric into a metric with a surface
forming null coordinate.
