1. Senior people leaving (as has been said by pretty much everyone else in this thread).
2. Not having a clearly defined problem to solve, or a well understood target audience.
3. Not knowing who the competition are, or just dismissing them as "not being as amazing as us."
4. Little or no customer research - if you hear the phrase "customers don't know what they want" and it's not immediately followed by "so we need to do research and find out" - run.
5. Building solutions that don't really map back to problems. This can manifest in a lot of ways, but the most common ones I've seen: projects constantly changing in priority (entire projects materialise and become urgent overnight), features that are arbitrarily demanded, or in an over-emphasis on polish and minutia.
6. Departments not collaborating, things getting thrown over the fence. Workflows that move in the wrong direction.
7. Lack of autonomy - a handful of people make all of the decisions.
8. Micromanagement. People tend to micromanage when things aren't going well, which tends to make them worse. It's a downward spiral.
9. Being afraid to talk to management about problems; being chastised for suggesting ways to improve things.
10. When mistakes are made, focusing on blame rather than resolution and prevention.