Maurice accidentally stepped on the back of my shoe, and the shoe flew (off or off of) my foot.
Both are correct, but I prefer to omit "of" because it's unnecessary.
http://public.wsu.edu/~brians/errors/nonerrors.html
In this sentence, the correct phrase to use is "off of." So, the shoe flew off of my foot. "Off of" is a prepositional phrase that indicates separation or movement away from something or someone. To understand why "off of" is the correct choice, let's break down the sentence:
1. Maurice accidentally stepped on the back of my shoe,
2. The shoe flew (off or off of) my foot.
To determine the correct phrase, we need to consider the verb phrase "flew my foot." To complete this phrase, we need to use the correct preposition after the verb "flew." In this case, "off of" is the appropriate choice because it indicates the direction of movement. So the correct sentence is: The shoe flew **off of** my foot.