Avengers: Infinity War - How ALL 18 MCU Movies So Far Tie In
6. Captain America: Civil War
Mentions Of Infinity Stones?
As this was an event movie removed from the main timeline because of the immediacy of the story, the Infinity Stones were pushed to the background. We know that Thor was off trying to find the Stones.
Relevant Story Details
The key point from Civil War to take into Infinity War is the state of the Avengers by the end of the movie. They're fractured and split apart, which is exactly how we'll find them at the start of the movie.
They might not hate each other any more (not that they really did), but the original Avengers are no more. Black Widow, Falcon and Cap are underground completing clandestine missions, Hawkeye and Ant-Man have "retired", Spider-Man is sent back home immediately and War Machine is almost fatally injured. It'll take some time to bring them all back together, which is basically the most important sub-plot in Infinity War.
Interestingly, the movie also showed the potential volatility between Vision and Scarlet Witch, which could also play a big role in how Infinity War ends. And presumably, we'll see the government's attempts to continue with the Accords, at least before Thanos turns up.