Is it possible to run 1000 lines of code on a single run with no errors??

Yes
Depends on the code and the language
A strict, uncompromising language like Haskell will make it easier to spot errors

If unittests do jot count as 'run', then yes, ez

Console.Writeline("hello world!");
......

1000 lines in a single file? Of course.. God knows how many thousands of lines my server hits when just handling one GET request...

Possible yes, but if its any complicated, probably not.

Then of cause it depends on what you define as error, only runtimes errors or logical errors.

As @RememberMe said, some languages makes it easier to avoid runtime errors but logical errors can be much harder to spot.

1000 lines of comments, yes

This is simple in python (end sarcasm)

Possible, but not probable. The accepted industry standard for production quality software is one defect per 1000 lines of code - in release!

@Fast-Nop I'll hard-limit myself to 999 lines now, dangit!