According to IMDB the alternate ending didn’t do well at test screenings, so they hastily reshot it. Here’s what was origionally shot;
Theo and Kee are in a building surrounded by the army who declare that the pregnant lady must surrender. At this point Kee says that she’d made the whole pregnancy thing up as she just wanted attention and extra welfare benefits, since she’d got a bit porky and her boyfriend dumped her. Theo goes into a rage, but then sees the funny side and begins to laugh. Kee joins in too and Theo leans out the window and tells the army what she’s just said, and they start laughing. Then the The Fishes hear what’s happened, and they start laughing as well, and so do all the immigrants. Then some wicked base starts playing and the quarantine zone becomes a party! Pop sensation Shaggy turns up with some of his homeboys and some scantily clad dancers to perform his hit song ‘It Wasn’t Me’ as the credits roll in a party atmosphere.