http://grammarist.com/usage/dreamed-dreamt/
Dreamed vs. dreamt
There is no difference between dreamed and dreamt. Both are considered correct, and both function as the past tense and past participle of the verb dream. Dreamed is preferred in all main varieties of English, but dreamt is especially common in British English; while American writers use dreamt about a tenth as often as dreamed, British writers use dreamt about a third of the time.
Dreamt is more often used in the figurative senses of the word—especially in the phrase dreamt up—while dreamed is more likely to denote the mental activity that occurs during sleep. But this is by no means a rule, and both words are used both ways.
http://grammarist.com/usage/hanged-hung/
Hanged vs. hung
Hung is the past tense and past participle of hang in most of that verb’s senses. For instance, yesterday you might have hung a picture on the wall, hung a right turn, and hung your head in sorrow. The exception comes where hang means to put to death by hanging. The past tense and past participle of hang in this sense, and only in this sense, is hanged.
When someone is hung out of malice but with no intent to kill, as described in the example below, hung is the conventional word:
They hung him by chains and tortured him.