Using : as a comment is not a good idea.
It's actually a null command, and does redirections.

Hersbrucker:Desktop$ echo $SHELL                     
/bin/zsh
Hersbrucker:Desktop$ echo "example text" > example.txt
Hersbrucker:Desktop$ cat example.txt                  
example text
Hersbrucker:Desktop$ : is this really a comment > example.txt
Hersbrucker:Desktop$ cat example.txt                         
Hersbrucker:Desktop$ ls -l example.txt
-rw-r--r--  1 mweeks  GSUAD\Domain Users  0 Aug 29 14:31 example.txt
Hersbrucker:Desktop$