Learn Spanish (Spain): Lo mismo la quedada se tuerce.

Even though lo mismo expresses probability or doubt here (meaning "maybe"), it is a colloquial expression that triggers the indicative. You don't use the subjunctive with it, unlike with quizás or tal vez.

Doesn't lo mismo usually mean "the same thing"?

Yes, literally it means "the same thing", but in colloquial Spanish (especially in Spain), lo mismo is frequently used at the beginning of a sentence to mean "maybe", "perhaps", or "chances are".

Is quedada related to the verb quedar?

Exactly. La quedada is a very common colloquial noun in Spain derived from quedar (to arrange to meet). It means a "meetup", "gathering", or "get-together" with friends.

How does torcerse mean "to go wrong"?

The base verb torcer means "to twist" or "to bend". When used as a pronominal verb (torcerse) regarding plans or situations, it metaphorically means things get twisted, or in English, that they "go awry", "go south", or "go wrong".