Here are a couple of patterns that I seem to be able to identify:
Retrospective replaces ad hoc problem solvingYou need a problem solved. The retrospective is a place to identify and solve problems.
Antipattern solution: Wait until the retrospective to raise the problem and get it solved.
Consequences: Problem resolution is deferred. The retrospective gets swamped with problems. Not enough time in the retrospective to solve all problems, let alone to explore what is not yet known.
Refactored solution: If you get aware of a problem, raise and solve it outside the retrospective. Enter the retrospective with an open mind to what new things you might discover and want to tackle.
Retrospectives as reporting to managementA problem is perceived to be only solvable with management involvement/approval.
Antipattern solution: Create actions that need management involvement or approval.
Consequences: Problem resolution is dependend on management taking action. If management has different priorities, nothing happens. Retrospectives degenerate into complain sessions, where you don't even expect to be able to make a difference.
Refactored solution: For every problem, come up with at least one action that doesn't need management involvement or approval, and will improve the situation at least a bit.
Result: Continouos improvement, however small. Team members get a better feel for the power they actually have. Managers see team members take initiative. They might even get interested in getting involved in the ongoing change.
Living in the (bad) pastRetrospectives are about looking back - they even have it in their name. And I remember a lot of problems I had.
Antipattern solution: Focus on talking about what happened. Focus especially on what went wrong.
Consequences: The retrospective becomes a depressive, energy draining meeting noone enjoys.
Refactored solution: Yes, look at the past - to share stories, to further understanding, and to paint a picture of a brighter future. Focus on what you have learned, on what you want to do differently (or the same!) in the future. Try an Appreciative Retrospective.
Result: A forward looking team with the energy to make a difference.
The Silver BulletYou have a deep rooting problem. Retrospectives are meant for problem solving.
Antipattern solution: Expect retrospectives, facilitated by someone who is barely trained for it, to be enough for solving your problem.
Consequences: The problem gets worse. Facilitator and group loose faith in retrospectives and their ability to solve this problem.
Refactored solution: Don't rely on retrospectives alone to solve your problem. Responsibly manage the problem. Get an expert involved.
Result: A chance to actually resolve your problem.