When planning the journey on the Grand Union Canal, the pair agree the first night at Rickmansworth, the second at Boxmoor and the third at Apsley. Geographically, Apsley is before Boxmoor and also the two places are only a mile apart, so would not both be overnight stopping points, even if in the correct order.
Several times the boats are seen traveling breasted up between locks, but when the crew are standing on the back talking, there is no propeller wash behind them.