  We use angle-resolved photoemission spectroscopy (ARPES) to image the
emergence of substaintial dispersion anomalies in the electronic
renormalization of the actinide compound UCoGa$_5$ which was presumed to belong
to a conventional Fermi liquid family. Kinks or abrupt breaks in the slope of
the quasiparticle dispersion are detected both at low ($\sim$130 meV) and high
($\sim$1 eV) binding energies below the Fermi energy, ruling out any
significant contribution of phonons. We perform numerical calculations to
demonstrate that the anomalies are adequately described by coupling between
itinerant fermions and spin fluctuations arising from the particle-hole
continuum of the spin-orbit split $5f$ states of uranium. These anomalies are
resemble the `waterfall' phenomenon of the high-temperature copper-oxide
superconductors, suggesting that spin fluctuations are a generic route toward
multiform electronic phases in correlated materials as different as
high-temperature superconductors and actinides.
