When Seaman "Happy" Hanes meets some Marines, he greets them by saying "Which one of you is John Wayne?" This movie is set in 1943. However, John Wayne didn't portray a Marine until 1949 in "The Sands of Iwo Jima".
During the opening credits, a helicopter fly-by shot zooms in on the PT-73, showing McHale and a seaman (in blue shirt and white sailor hat) at the helm. In the next shot, as the PT-73 pulls up to an island dock, McHale and Ensign Parker are at the helm.