vor versammelter Mannschaft — in front of the assembled crew. The Duden dictionary’s example comes from the army: der Gefreite wurde vor versammelter Mannschaft getadelt, the lance corporal was reprimanded in front of the assembled unit. In everyday speech the phrase means in front of everyone present. Mannschaft can also mean a work team.
jemanden zur Rede stellen — to put someone to the speech, to call someone to account. Duden notes that Rede here first meant a statement or a justification before a court.