There are two major ways that the Tor developers could fuck us if they really wanted to or were forced to. For one they own the majority if not all of the directory authority servers, it is possible for them to lie and say only nodes they own are part of the Tor network. This would allow them to become a global active adversary, which means that they could entirely defeat all security advantages of Tor for all of its users, but it would require them to own the amount of bandwidth required to relay all Tor users traffic. This would not be possible for them to do without some people noticing all of the node IP addresses suddenly changed, but the Tor client does not warn you if such a strange event happens, and you will need to look for yourself or wait for someone who realizes to point it out. They take some protections from this though, for one the people who run the dirauth servers and the servers themselves are situated in a few different international jurisdictions around the world. Also, four out of nine servers need to agree to a consensus, so at least four of them will need to be compromised (via force or via bribes) by cooperating attackers. The people who run the dirauths seem to be largely libertarian, and I think they are absolutely opposed, with firm moral grounding, to compromising the Tor network in any way. Another possibility is that they could bug the code, but this would eventually be detected in an audit and might never get added in the first place. I believe they also have the full support of EFF when it comes to dealing with legal matters, and that EFF claims they will take any attempts to force the Tor developers to backdoor their product in any way to court, and they think that they will win in USA anyway.