A classical and semiclassical investigation of conditions required for the observation of a Condon reflection pattern in the products state distribution for the collinear H + Cl₂ reaction is reported. Both vibrational and translation excitation of the reactants are considered. The use of semiclassical arguments in this context is justified by a high level of agreement with exact quantum mechanical results, although a significant threshold anomaly remains to be investigated. Competition with the inelastic channel above a certain threshold, which decreases with increasing reactant vibrational quantum number, is found to invalidate any simple Condon reflection prediction. The nature and importance of this competition is shown to be simply characterisable in terms of the properties of certain trapped trajectories, or nascent transition states, in the products valley of the potential surface.