[en] Contribution from a triangle diagram corresponding to the proton-deuteron rescattering in the final state, to the tp → pnd reaction amplitude at psub(t)=2.5 GeV/c, is calculated. The pd half-shell scattering amplitudes, obtained from solution of scattering integral equations were used in the calculation. The qausi-free pn scattering mechanism enhances the theoretical spectra as compared with the experimental spectra, in the kinematical region corresponding to emission of a fast neutron. It is shown that the contribution from the triangle diagram does not improve agreement with the experiment, because the interference term is small. The latter fact results from compensation effects due to the half-shell behaviour of the proton-deuteron scattering amplitude. The contribution from the triangle diagram to the total cross section amounts to about 10% of the contribution from the quasi-free scattering diagram