Cragen's Limited Advancement Opportunities (he's been at the same rank for almost 25 years) makes a lot more sense if you recall that, at the end of the first season of the mothership, he helped send the guy who had gotten him all his previous promotions to prison for corruption.
The whole show makes a lot more sense when you realize that it's not meant to be a realistic portrayal of the American justice system, but rather a Stealth Parody of its flaws.
In the episode Padre Sandunguero, Barba loses what should be a slam-dunk case, implied to have failed because he was being reminded of his own possibly abusive father. The brilliance comes when you realize, between Barba clenching his fists during his cross-examination (a habit he admits he has when he thinks of his father) and the fact that Barba later says he doesn't understand how the cross-examination got away from him, because he's "known guys like this his whole life". In short? Barba lost a slam-dunk case because he thought he was questioning his own father, not someone's else.
Often tends to crop up when things deemed unnecessary to the flow of the story are ignored by the writers. For example, it is never explained where a fifteen year-old boy who had slept with dozens of hookers was getting the money for the high-priced call girls he was seeking out.
It's implied his family is at least well off. He proably has a trust fund or something, like every other teenage suspect on SVU.
Also, Ariel is a genderless character in Shakespeare's The Tempest, who has been played by both men and women.
Elliot Stabler frequently bends or outright breaks the law to torture suspects (who more often than not turn out to be innocent and are often killed as a result of this), but for some reason the only thing that's brought up to internal affairs is the fact that he sometimes wishes rapists would die.