Early in the film Stanley Baker has a conversation with one of his officers about having Zulu chiefs on a flight. A few years later he would be the lead in probably his biggest film role as lieutenant Chard in the film Zulu .
If I don't do something soon, I'll explode.
Such an aircraft suffering a catastrophic decompression would not suddenly dive out of control. The pilot would deliberately place it in a shallower spiral descent, to increase cabin pressure and temperature, while maintaining a sense of gravity. To avoid the need for oxygen masks, an altitude of less than 10,000 feet would be required.