Designated Hero: The film treats Dave, Ellen and Duane as heroes despite - or because of - the fact that by not denouncing the substitution they subvert democracy and the US Constitution, effectively depriving the American people of the government they voted for. (Then again, considering a not insignificant number of the other members of the legitimate government were indicted...). It should perhaps be noted that Dave himself only continues the charade because he's convinced by others (for their own self-serving ends, granted) that the Vice President is secretly a dangerous lunatic who shouldn't be in power, thus making the situation from his point of view a necessary evil to prevent a worse outcome — and once he realises he's been lied to, he makes a point of ensuring that the rightful transfer of power can take place as quickly as possible, but in a way that ensures that more guilty parties also receive their just comeuppance and also makes a point of letting everyone know that the Vice President was completely innocent.
Hilarious in Hindsight: The First Lady of the United States can't even bear to hold hands with her husband as soon as the public isn't watching. Who'd have thought that possible?
Love to Hate: Bob Alexander is a truly horrible, amoral person who cares only about his own power and doesn't give a damn if he hurts the whole country to get it. But Frank Langella plays the role so well and with such scenery chewing gusto that he's a joy to watch, especially when he finally receives his comeuppance.
Magnificent Bastard: White House Communications Director Alan Reed is a canny politician who aids President Bill Mitchell and Chief of Staff Bob Alexander in various acts of corruption. When Mitchell has an incapacitating stroke, Alan smoothly gets the medical staff and the Secret Service to keep the situation a secret, frames Vice President Nance for corruption so that Bob can become Vice President, and convinces Mitchell's lookalike Dave Kovic that impersonating Mitchell is morally justifiable and vital for national security. Alan coaches Dave on how to impersonate Mitchell, eventually evolving to see Dave as a friend and leader. When Bob turns on Dave due to his sense of independence and desire to do good work, Alan sides with Dave and helps him try to improve the country. When Bob exposes Mitchell's crimes to bring down Dave, Alan supplies evidence of Bob's complicity in those crimes. Alan helps Dave fake another stroke and return to his old life, avoids being indicted along with Bob, and goes on to serve Nance, the man who he framed before his eventual Heel–Face Turn.
Memetic Mutation: "I once caught a fish this big!" and "we're walking, we're walking".
Alexander objects to Dave beginning to act like an actual president, saying, "Was he on the Trilateral Commission? Was he a senator? Was he in Who's Who in Washington nine years in a row?" Granted, Alexander is totally corrupt and Dave certainly shouldn't be following his orders, but he does have a point that Dave is probably unqualified to be president himself.
Alternatively, the point of the movie is that all you need to be a good president is compassion and common sensenote Things that are mainly denied to a major political figure due to the nature of the office, and the promises and deals necessary to get there. In other words, Dave is the perfect president because he didn't have to do anything to get there.
Even so, Dave is a great deal more qualified than the former President Mitchell because he calls in experts to help him do his job. The only reason he's able to find the money in the Federal Budget is he actually listens to his advisers while making his demands to find and cut unnecessary programs clear. Mitchell was implied to not care enough/desired to keep his hands on the reins of power no matter what.
While the movie doesn't go overboard, the cameos by politicians of the era clearly mark this movie as something of the early '90s.
Ditto the scene of "President Mitchell" throwing out the first pitch at a Baltimore Orioles baseball game; before the Montreal Expos were relocated and became the Washington Nationals in 2004, Baltimore was the closest team to DC.
The Scrappy: The titular Dave is the least popular main cast member due to being perceived as a jerk who frequently gets away with his shitty behavior.
Unintentionally Unsympathetic: While the show has received generally positive reviews, the Dave character has not been well-received. Dave treats each of the other main characters poorly at least once but does not face any real repercussions aside from Ally dumping him at her sister's wedding. The other characters have been well received, however.
