Errors appear on localhost and not on actual site

[diy]

For example this

 

Notice: Use of undefined constant NONSSL - assumed 'NONSSL' in.......column_right.php on line 57 (I use the adsense box contribution)

 

Appears on localhost on column right but there is nothing wrong with the actual site

 

Is it possible that other people with other browser settings can see this notice????

 

PS How do we force the browser to show us the parse errors !!