Tone is a range of light to dark imagery, ideas and subject matter that the movie will cover. The place to set the tone is in the first scene. The first scene primes the audience for the type of experience they are going to have. A good rule of thumb is to establish your tonal range in the first scene.
If your movie aims to have a broad tonal range, you want to do something like GUARDIANS OF THE GALAXY and establish that broad range in the very beginning. GUARDIANS OF THE GALAXY goes from a dying mom to an alien abduction, through a big 20 year jump in time, to dancing with a Walkman on an alien world. This works to establish the most serious subject matter the movie will cover, and when it comes back later it’s not a shock as we’ve established the movie’s tonal range from the very start.
Other comedies with some more serious subject matter, and as a result, a wider tonal range, smartly establish this range in the very first scene.
SAFETY NOT GUARANTEED does this too, opening with a life montage that establishes the characters personality and the fact that her mom died. The darkest element of the story is on display in the first minute of the movie and the scene ends on the type of lighthearted joke that makes up the bulk of this movie.
The first scene is also a good test study to discover if your tonal range is too wide.
Since The hero in SAFETY NOT GUARANTEED is talking about her dead mom in the very beginning, it would certainly feel out of place for us to end the scene with a joke that goes too far — is too over-the-top, zany or gross. When you ground the story in something that’s as serious as a dead parent, you can’t go as far on the humor end of the spectrum. Having a dildo falling out of our hero’s purse, right after she’s told us her mom is dead, doesn’t work in a scene and arguably is too broad a tonal range for this movie.
GUARDIANS OF THE GALAXY also carefully presents the first scene, not going too far with the comedy after we’ve just witnessed the hero’s mom die. They also, smartly take us 20 years into the future, so mentally we know the hero has had time to heal. This time jump occurs in SAFETY NOT GUARANTEED also, though the time jump is not as wide.
One movie that had notorious “tone” issues spelled out through it’s rotten tomatoes reviews is TUSK. I would argue that the movie’s issues are less a product of an overly broad range of subject matter and more of an issue with establishing the tone in the first scene.
Nothing in the first scene of TUSK prepares you for how deep into the horror genre this movie is going to go. There are scenes that are truly disturbing. I would argue here that those scenes are only tonally disturbing because we have not been primed to see them in the correct context — a context that’s funny.
TUSK forgoes preparing us for a true horror-comedy and establishes an edgy (there’s Nazi jokes) indie comedy. There is perhaps the minor attempt to prepare us for what will come with the kid in the video slicing off his leg, but the intensity of that “horror” is far too weak to establish the complete movie’s tone — the kid slicing off his leg is a “one” on the horror meter when it needs to be a “ten,” since ultimately that’s where this movie is headed.
I should also point out that many movies have a narrow tonal range, making establishing this range easy and often done instinctively by the writer. Serious movies like SAVING PRIVATE RYAN, SCHINDLER’S LIST, or FURY have a narrow tonal range that easily establishes both tone and genre in the first scenes. But, the wider the tone, the more important establishing it becomes. Genres like horror-comedy, or sci-fi comedy stretch at the boundaries of genre itself, so careful attention must be paid to that first scene, so your audience knows what to expect from the very start.