Continuity mistake: The tyres on the crotch rocket motorcycles they were riding kept changing from knobbly tyres to road slicks, back and forth depending on what terrain they were on. Easiest to see when Ethan skids on the road to avoid the white van - clear shot of slick tyres - then about 30 seconds later they're on the dirt, he skids into the old car and you can easily see that he's got off-road tyres front and back.
Factual error: In the scene at the race track where they show the virus infecting and destroying cells in the blood stream, they clearly show that it is red blood cells being infected. Viruses, in order to replicate, require the cell's DNA replication machinery. However, mature red blood cells in the circulation no longer possess this machinery since they no longer have a nucleus or DNA. It would therefore be impossible for this virus to replicate.
Continuity mistake: In the car chase scene with Nyah after they split and hit again and are spinning look at Ethan's car. The driver's side in the close ups was on the American side, then in the spin it is reversed to an English side. (It is a negative image - the license plate is reversed). The next image is back to normal.
Trivia: In the movie trailer Tom Cruise greets Ving Rhames when he lands in a helicopter on a remote property in Australia. He says "Welcome to Australia, mate" with an attempted Aussie accent on the word "mate". But that line was never shown in the movie. Not sure why. Perhaps the producers thought that it may come across as Tom mocking Australians?
Sean Ambrose: You know women, mate. Like monkeys, they are - won't let go of one branch until they've got hold of the next.
Sean Ambrose: In just a few hours you can be assured of going down in history as the typhoid Mary of "Aus." G'day.
Question: Why didn't Ethan just give Nyah one of his guns after she infected herself? She could have easily killed Ambrose and others with a surprise attack since they were more interested in keeping her alive and she wanted Ethan to kill her anyway. She had better odds of surviving that way than the impossible plot that followed. She could have killed everyone but Ambrose and he may have let it happen in order to still have a chance at selling the virus.