Hole 1 specifies returning the fifth word; your solution returns some extra whitespace. Additionally, there may be no whitespace after the fifth word, or after any of the words: first-second!third+fourth*fifth.
For Hole 3, the entire string must consist of the repeated substring. This was demonstrated in the examples, where 'ababab' results in 'ab' but 'ababaaa' results in ''.
Hole 4 asks for a list of characters, rather than a string. Looks like that one tripped up a lot of people. :)
Hole 5 features a common gotcha; a correct solution must handle the case where all the values in the list are negative. Another one that a lot of people don't catch. :)
We tried to make things a little easier at the actual tournament by providing a test scaffold for each hole, which the participants could use to test their code on sample input. Solving these holes is much harder without that.