While on the phone with Logan, Graem mentions the damage that would be done to the country by a sitting president on trial for the murder of another president. Though not technically a law, an unwritten understanding is that, while in office, the president can't be indicted for crimes he commits; he would first need to be impeached by the House of Representatives and removed from office by the Senate. And if Logan were removed, he thus wouldn't be a sitting president; immediately upon his conviction, his vice president, Hal Gardner, would be sworn in as president.
Jack Karen, Bill, and Jack wouldn't have been able to call each other over their cell phones when Jack was on the plane because there's no signal at that altitude.
When Chloe has almost finished cleaning up the recording, Miles' destroying of the original wouldn't have prevented playing it as she would have been working on a copy of the recording on her workstation and that copy would have been preserved unless he also destroyed her workstation which wasn't the case.
Just as Jack's plane is about to land on the freeway, a series of white stripes can be seen on the road. These appear to be runway touchdown markers, not something normally seen on freeways.