Depending on language, "Hello World" may inherit bugs from the compiler used to produce its binary. Otherwise, it gets its bugs from the interpreter or VM.
Even "hello, world" itself has many bugs in many implementations.
I mean, do you check to see that stdout is actually connected before you blindly output? Or do you just output and hope for the best? ("hello, world" that doesn't print "hello, world" would be considered a failure).
Do you check all return values? Do you even know that printf() in C has a return value?
Did you check that the output buffer has sufficient space for your characters, or are you assuming your program won't hang because the output buffer is full?
Does your language startup/shutdown routines properly handle your return type? I mean, if you're doing the "void main(void)" thing, is your startup code making an assumption that you're returning an int? Sure it might do the right thing most times, but perhaps it suddenly blows up and instead of returning 0, it returns -238 or something.
Etc. Etc. etc. It's a good way to test how good someone is at QA testing - give them a standard version of "hello, world" and have them figure out all the bugs that can be lurking in it.