Revealing mistake: When we see the bees flying off the trash cans and on their way to Marysville, you can see it is simply reversed footage.
Revealing mistake: If you look carefully when Paul's father is killed by the bees at the picnic site, you can see he is breathing as his belly is expanding.
Revealing mistake: When the bees attack the train during the evacuation scene, a guard falls backwards and his arm hits a lever. You can see that the 'bees' in this scene are just colored pellets.
Revealing mistake: When Felix puts down his cup of coffee whilst speaking to Mr Harris in the cafe, you can see his cup is empty.