When Collins is describing to Skippy the people photographing the hatch crane, he repeatedly says they were standing on the "boat deck." On a lake freighter, the deck containing the hatch covers and the hatch crane is called the "spar deck,' which one would expect a lakeboat officer to know. The "Boat Deck" is at the stern, one deck higher than the spar deck. It would be possible to see and photograph the hatch crane in operation from the boat deck on most lakers, but the company guests are shown standing next to the hatch cover, on the spar deck.
At points in the movie crew members are shown making phone calls to shore via the inter-ship phone system. That phone system only allows calls to other parts of the vessel.
Longshoremen are shown moving around bulk cargo on pallets when the ship is in port, despite the fact lakeboats are filled with coal, grain or iron ore. They never carry modular bulk cargo.