In "5/1", the flight attendant's insistence on Don staying quiet and in his seat seems to just be a convenient plot obstacle to keep Don, Elliot, and Sloan from getting to ACN — until you remember that it's not paranoia to be scared of someone taking control of the cabin after the events of 9/11. The implications of his protests visibly hit Don in the face when he remembers just what they're so desperate to report — and why they're so desperate to report it. It's also a United Airlines flight crew, which staffed two of the four flights involved in the 9/11 attacks.
Every time a character makes a Don Quixote reference its more accurately a reference to Man of La Mancha, an adaptation that takes a specific interpretation of Don Quixote that is much more applicable to the messages of the show than the complexity of the original novel.
In season 3, when Jenna, Will's intern, brings him yogurt and a banana for breakfast, Will asks if she has been taking direction from him or MacKenzie. She claims it's always been MacKenzie, which makes sense since we learn MacKenzie encouraged her to ask the question that prompted Will's The Reason you Suck speech about America.
Will used to work at the White House, and has connections at the highest levels of government — his contact at the State Department is heavily implied to be Hillary Clinton, then Secretary of State. When the news breaks about the shooting of Representative Gabrielle Giffords in Tucson, and Will slips and calls her "Gabby" on air, it's not just sentimentalism — it's entirely possible that Will knows Gabrielle Giffords personally.* This becomes even more likely when you consider their relative politics; Giffords, as a centrist "Blue Dog" Democrat, would have more in common with moderate Republican Will than either of them would have with some of the more extreme members of their own parties. This could very well be a man reacting to hearing that a friend has been shot and is not expected to survive.
