Find all the Anagrams!

05AB1E, 3 bytes

œÙ¦

A function that leaves the stack with a list of the anagrams on top (and as its only item). As a full program prints a representation of that list.

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How?

    - push input
œ   - pop and push a list of all permutations (input appears at the head)
 Ù  - pop and push a list of unique items (sorted by first appearance)
  ¦ - pop and push a dequeued list (removes the occurrence of the input)
    - As a full program: implicit print of the top of the stack

Ruby, 45 bytes

->x{(x.chars.permutation.map(&:join)-[x])|[]}

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Despite having a built-in, the word "permutation" is really long :(

pyth, 8 4

-{.p

Online test.

  .pQ     # all permutations of the (implicit) input string
 {        # de-duplicate
-    Q    # subtract (implicit) input