I don't know, but it looks like the combo of backticks and the `( )` array assignment.

I don't have much time to investigate, but this snippet fails in zsh:
```
function test1 {
  local VAR1=( `ls` )
  echo ${VAR1[1]}
}
test1
```

But it works fine if I remove the `local`, or split the declaration and assignment like so:
```
  local VAR1
  VAR1=( `ls` )
```