  A semiconducting nanowire with strong Rashba spin-orbit coupling and coupled
to a superconductor can be tuned by an external Zeeman field into a topological
phase with Majorana zero modes. Here we theoretically investigate how this
exotic topological superconductor phase manifests in Josephson junctions based
on such proximitized nanowires. In particular, we focus on critical currents in
the short junction limit ($L_{\rm N}\ll \xi$, where $L_{\rm N}$ is the junction
length and $\xi$ is the superconducting coherence length) and show that they
contain important information about nontrivial topology and Majoranas. This
includes signatures of the gap inversion at the topological transition and a
unique oscillatory pattern that originates from Majorana interference.
Interestingly, this pattern can be modified by tuning the transmission across
the junction, thus providing complementary evidence of Majoranas and their
energy splittings beyond standard tunnel spectroscopy experiments, while
offering further tunability by virtue of the Josephson effect.
