Quantum field theory in curved spacetime has contributed greatly to our understanding of physical scenarios where both gravity and quantum theory are important. It plays an essential role in how we think about the problem of quantum gravity and is in some sense a bridge to it. There have been many technical and conceptual developments in QFT in curved spacetime over the past few decades. Nevertheless, deep and challenging open questions remain, and the right direction to answer them can be obscured in the absence of observational tests or input from quantum gravity. In this talk I will discuss some insights that have come from considering quantum fields on discrete causal sets, which are a proposed fundamental structure underlying spacetime in the causal set theory approach to quantum gravity.