is it possible that he could contact this company and put a bad word
in, and that they would take it into consideration and possibly
rescind my offer?
Anything is possible. And you know your friend more than we do, so know better if he would actually do such a thing.
That said, I can't imagine I'd take some random stranger's "bad word" into consideration when making a hiring decision.
Unless your friend already has some connection with this company, it's extremely unlikely that he could exert any influence without the hiring manager at least asking you about it.
I might be being paranoid here, but all I know is that if he were to
ruin this for me, I'd be really, really depressed about it. Do
employers know that this type of vindictive behavior happens? The
company in question is not a small one. Should I be worried, or is
there anything I can do to make sure he isn't able to sabotage my
I once performed a reference check on a candidate. The person I spoke to casually mentioned that the candidate's nickname was "zipperhead" (the candidate was not Asian, but had a scar from a motorcycle head injury).
In my circles, that wouldn't be a term of endearment.
So I spoke to the candidate, and mentioned what the reference had said. The candidate explained that his reference was also a childhood buddy, and kidded around like that all the time.
I ended up hiring "zipperhead" - and he turned out quite well.
In the unlikely event that the saboteur actually contacts this company, I can't imagine the hiring manager just dropping you from consideration without giving you a chance to speak for yourself.
And should the hiring manager take a random caller's word without providing a chance for you to speak, it seems to me that you wouldn't want to work for such a manager anyway.
If it were me, I wouldn't be worried.
(Note: I understand how the word "zipperhead" might be used these days. The person in question wasn't of Asian decent. And I don't think that term had that context in those days (it was a number of years ago). The individual had a head injury from a motorcycle accident that left a scar. That was how his references used the term. Still not nice, but nothing at all racial about it. Just some goofy friends.)