Continuity mistake: During the plane and semi scene the front of the semi gets shot to pieces. If you look at the windscreen when the semi comes back onto its wheels it's more like a protection cage, then in the next shot it's gone.
Continuity mistake: The wounds on John's right eyebrow and cheekbone change size, disappear, and switch from fresh to dry then back again throughout the film.
Continuity mistake: When John drives over the fire hydrant and the water jet hits the helicopter, the gunman falls out and ends up on the ground between the car and water jet. When John drives off in the long shot his body has disappeared.
Continuity mistake: When Detective Maclean is trying to convince Matt to go with him, Matt tries to open a window, so he can escape, but the window won't open. Later, after all the gunfire, both men escape through the now-working window.
Chosen answer: In 2005, Hurricane Katrina ravaged the city of New Orleans, with many of the residents temporarily housed in the Superdome. FEMA (Federal Emergency Management Agency) was highly criticized for their response (or lack of), including how long it took to supply the Superdome with adequate water and food. Matt's pointing out to John how the government isn't nearly as capable of responding to disaster as people think.
OneHappyHusky