  Planetary nebula (PN) surveys in systems beyond ~10 Mpc often find
high-excitation, point-like sources with [O III] $\lambda 5007$ fluxes greater
than the apparent bright-end cutoff of the planetary nebula luminosity function
(PNLF). Here we identify PN superpositions as one likely cause for the
phenomenon and describe the proper procedures for deriving PNLF distances when
object blends are a possibility. We apply our technique to two objects: a model
Virgo-distance elliptical galaxy observed through a narrow-band interference
filter, and the Fornax lenticular galaxy NGC 1380 surveyed with the MUSE
integral-field unit spectrograph. Our analyses show that even when the
most-likely distance to a galaxy is unaffected by the possible presence of PN
superpositions, the resultant value will still be biased towards too small a
distance due to the asymmetrical nature of the error bars. We discuss the
future of the PNLF in an era where current ground-based instrumentation can
push the technique to distances beyond ~35 Mpc.
