Some hard-to-spot but occasionally useful rules, for when you've mastered all the others.
The 1's never appear as all "actual" 1's; at least one is an "effective" 1. The mine is always behind the middle 1, and the other two are safe:
Like the Three Trapped 1's, at least one of the 1's is an "effective" 1. The first and fourth squares will be mines, and the other two safe: