QCD Interconnection Effects \\ in Hadronic $W^+W^-$ and $t\bar{t}$ Events

In the events of the type $e^+e^- \rightarrow W^+W^- \rightarrow$ 4 jets, $e^+e^- \rightarrow t\bar{t} \rightarrow bW^+\bar{b}W^-$, particle production could depend in a non-trivial way on the kinematics of the process. It is shown that QCD interference effects are negligible for energetic perturbative emission, but soft perturbative gluons and non-perturbative fragmentation could induce colour correlations. Possible consequences for LEP 2 and NLC events are briefly addressed.