  We review an algorithm for determining the branch points of general
amplitudes in planar $\mathcal{N}=4$ super-Yang-Mills theory from amplituhedra.
We demonstrate how to use the recent reformulation of amplituhedra in terms of
`sign flips' in order to streamline the application of this algorithm to
amplitudes of any helicity. In this way we recover the known branch points of
all one-loop amplitudes, and we find an `emergent positivity' on boundaries of
amplituhedra.
