Writer David Mamet has actual experience sailing on cargo vessels where he worked as a cook.
At about 52 minutes into the movie, the Seaway Queen is shown entering a huge, boxlike structure, one of six shown in the frame. These are the famous Flight Locks on the Welland Canal at Thorold, Ontario, which raise and lower ships a total of about 150 feet in three stages, upbound (toward Lake Erie) or downbound (toward Lake Ontario). Basically, it's how you get a giant cargo ship around Niagara Falls. You can see the Flight Locks from the observation platform from Lock 3 at the regional museum at St. Catharines. The camera's POV appears to be near the top of the Glendale Avenue lift bridge, which is on the road to Niagara Falls.
The ship used in the movie is the S.S. Seaway Queen a 713' Canadian Great Lakes bulk freighter, built in 1959 and operated By Upper Lakes Shipping of Toronto, Ontario, Canada. For the movie Toronto was painted out on the stern and replaced with Chicago. She was sold for scrap in 2003.
The verse from Rudyard Kipling quoted in the film and seen written on a piece of paper read: "Dawn in the Foreland And the Grey Seas Breaking Mines reported along the chain. Sent up, Minesweepers, Stormcock, Claribel, Good Counsel, Assyrian, and Golden Gain." This is a varied form of the text that appears in Kipling's 'Mine Sweepers' (1914-1918) poem.
Based on an early David Mamet play, which ran at the Tiffany Theater in West Hollywood, California, with the same cast.