Corrected entry: When the crew is getting in the fire truck near the start, the camera man gets in after the presenter. Next thing, they've switched sides. There was no room for them to switch sides.
Corrected entry: The people who get bitten early on in the film take several hours to develop any symptoms. Then once they start biting people everyone develops symptoms within minutes. The doctor says that the incubation time varies with blood type, but it's beyond willing suspension of disbelief that the first victims all share the same blood type that is resistant while the later victims all share the same blood type that is barely resistant at all.
Correction: The doctor only said that some blood types are resistant and some aren't, he never said which types. It's possible that only 1-2 blood types is highly resistant while all others offer very little. They all took different times to turn (the doctor took a few minutes,the original policeman took approx 20 for example), so it's possible the first woman just had very resistant blood.
Correction: There is enough room for them to switch sides and plenty of time for them to do so in between shots.
Jack Vaughan