From the introduction:
This adventure can be can be easily customized to a party of any size or level, or run as a level 3 adventure for 5 players. It can work as a small side adventure in an existing campaign, as a standalone one-shot, or the start of a new adventure. Use the links to the tools in their relevant section to customize the adventure to your party.
One of the party members is actually the mastermind of the time travel malfunction, set in motion to change the fate of someone or something from their backstory. Speak with one of the players before the session to set up the details of this event from their past that they want to change, and tell them that they'll need to keep it a secret in order for their plan to work.
The PCs start in a hamlet in the desert, looking for info related to their backstory or doing downtime. A spell goes awry and the PCs need to deal with a bunch of summoned reflections. The reflections think they're the real ones and are confused about the PCs and how they got here. Try to roleplay the reflections similarly to their respective PC, but with a detail changed. If a fight breaks out use the PC's own statblock, but the reflections will disappear after some time has passed (and hopefully before any serious harm is done).