A few interesting ideas for having retrospective at a larger scale than the single team.

Neat tools to keep retrospective fresh. If people settle too much in habits they quickly become dull.

Interesting alternative retrospective format. The way of framing the questions might help get new ideas.

Interesting set of follow up questions during a retrospective.

Interesting first set of antipatterns... I clearly already encountered the "In the soup" and "Loudmouth" ones. This is like a long advertisement to the book of course but I think I'll try to get my hands on it.