The shootout at the beach house was filmed in 28 days; 20,000 rounds of ammunition were fired. The final shootout at the church took 36 days and 40,000 rounds.
Took 92 days to film, with a budget of 14 million Hong Kong dollars (2 million US dollars).
The film did not do well in Hong Kong because audiences didn't like the allusions to the Tienanmen Square massacre.
Jeff and Li's "Mexican standoff" in Jennie's apartment was inspired by Sam Peckinpah's "The Wild Bunch". Woo notes on the DVD commentary that Mad Magazine's "Spy vs. Spy" also played a part in constructing this scene.
The shootout on the tram caused chaos in the Causeway Bay district because people thought a real robbery was going on. John Woo had to talk to the Police Superintendent himself before he was allowed to resume filming.
All of the guns seen in the film are real. Because of Hong Kong's very strict gun laws, they had to be imported and their use on-set was closely monitored.