1x08 introduces Buttercup, a dog with cancer. Owen adopts him. They worry the cancer has come back in 2x11 but it hasn’t; Buttercup is fine. As of the end of season 4, Buttercup is still alive.
A transgender character who has transitioned mentions his experiences at various times throughout the series. At one point he is surprised with a picture of himself pre-transition, which upsets him. However, he does not explicitly mention body dysmorphia as the reason.
This episode shows multiple instances of stalking. A man stalks multiple people, showing up at a public event to threaten them. Other characters stalk him in return. A woman has been stalking a man she has a romantic obsession with and assaults multiple people in his life to get closer to him. This storyline is 3x11-3x12.
A main character describes how he drank too much after a traumatic event, which contributed to the decline of his marriage. He is shown drinking multiple times throughout the series, sometimes to excess.
Around 5min 48sec, the scene changes from the call center to the site of the accident where the cop car hit a deer. Closeup of the deer, including red liquid / blood.
In the starter scenes, a group of people at a wedding begins vomiting a lot until around 1/3 into the episode. They mention smelling it multiple times throughout the episode
A main character has PTSD as the lone survivor of his entire firehouse in an explosion a year prior to the pilot episode. It is the focus of his character throughout season 1.