  We study how close-in systems such as those detected by Kepler are affected
by the dynamics of bodies in the outer system. We consider two scenarios: outer
systems of giant planets potentially unstable to planet--planet scattering, and
wide binaries that may be capable of driving Kozai or other secular variations
of outer planets' eccentricities. Dynamical excitation of planets in the outer
system reduces the multiplicity of Kepler-detectable planets in the inner
system in $\sim20-25\%$ of our systems. Accounting for the occurrence rates of
wide-orbit planets and binary stars, $\approx18\%$ of close-in systems could be
destabilised by their outer companions in this way. This provides some
contribution to the apparent excess of systems with a single transiting planet
compared to multiple, however, it only contributes at most $25\%$ of the
excess. The effects of the outer dynamics can generate systems similar to
Kepler-56 (two coplanar planets significantly misaligned with the host star)
and Kepler-108 (two significantly non-coplanar planets in a binary). We also
identify three pathways to the formation of eccentric warm Jupiters resulting
from the interaction between outer and inner systems: direct inelastic
collision between an eccentric outer and an inner planet, secular eccentricity
oscillations that may "freeze out" when scattering resolves in the outer
system; and scattering in the inner system followed by "uplift", where inner
planets are removed by interaction with the outer planets. In these scenarios,
the formation of eccentric warm Jupiters is a signature of a past history of
violent dynamics among massive planets beyond $\sim1$ au.
