Just Let Go - S1-E4
Revealing mistake: When Lexy falls through the railing, there's a few shots where you can tell she's been replaced by a (probably adult) stunt double. She suddenly seems quite a bit taller, and noticeably has more muscle tone in her legs.
Just Let Go - S1-E4
Revealing mistake: During the flashback, when Charles shows the kids the body of the janitor, in the first close-up of the Janitor's face, you can see a pulse in his neck. (The next time you see his neck, you can also see a slight pulse, albeit, it's much, MUCH subtler in this shot.)
Just Let Go - S1-E4
Revealing mistake: When we see the outside of the hospital in the beginning, as the camera cranes down to see the ambulance, you can see a subtle sort of "blur/feathering" around some of the tree branches and leaves above. The background appears to be added in post, and the foreground tree just wasn't quite blended in properly.
Answer: They were blamed for the death of Jake's foster brother, which was deemed a terrible accident, and they were sent to the reform school as a punishment. Presumably, when they had to leave the reform school given what happened, they were instead given community service as punishment.
TedStixon