Although Hess did parachute at the end of his flight to Scotland, he wasn't "dropped" as Captain Mainwaring says, as that implies others being involved.
Shadow of a boom mike as Walker talks through the letterbox of number 28.
It is established early on that the British parachutes are white and the German parachutes are cream colored. However, when the white parachute is found, the platoon immediately begins searching for a German, even though it must be British.
British pilots who parachuted to safety were required (if possible) to retrieve their parachutes and return with them, as silk was a scarce commodity. Therefore it was extremely rare for a British chute to be found.
When Mainwaring is knocking on doors trying to determine what color the parachute cloth was, the people he disturbed appear with Hodges, the air raid precautions warden. He would have had no authority in this matter- they should have called the police.
When Mainwaring, Wilson and Jones are together after the platoon have left with the dog Mainwaring calls Jones "Walker" in a fluffed line.
When Jones demonstrates how to react to aircraft fire, he says his body is resting on his right arm. It's resting on his left arm.