Tom Segura's tinder date was played by his real life wife.
The app featured in the film actually exists. It is owned by the studio and was used to promote the film. If you download it, it gives you a time until death. But if you delete it and download it again, it gives you a different time.
Some of the places in the abandoned part of the hospital were filmed in the same place as the tv show Teen Wolf. These include the locker room and the hallways as they are notably the same.
When the app notifies the "victim," the scream you hear is from Bungie's game Destiny. It uses the scream of Omnigul.
When filming ended, Tom Segura "celebrated" by sleeping on the toilet.