How about holodeck episodes?
Recurring themes in holodeck episodes:
1. Characters get trapped in the holodeck, and can't end the program or physically exit the compartment
2. The safety protocols are overridden, or offline
3. Holographic characters become sentient, or self-aware
The holodeck became a crutch for the writing staffs of TNG and the spinoffs, and was used in far too many episodes.