“Games give you a chance to excel, and if you're playing in good company you don't even mind if you lose because you had the enjoyment of the company during the course of the game.” ― Gary Gygax
Covered in the KS FAQ:
Will the cards included in this expansion be compatible with current edition I own?
First, this is an expansion, it requires a copy of The Resistance to play.
That said there is no practical way to ensure that every print run (and there have been many of The Resistance) is the exact same. So I am sure that there will be some card print differences between these expansions and your copy of The Resistance. That will be true of the smaller box, 1st edition and likely with different print runs of the 2nd edition. In most cases I would suggest opaque backed card sleeves to hide those differences.
There are some card differences for the 1st edition (small box) edition of The Resistance: Trapper Module - uses an extra team token, which in the first edition was a card. Trapper Module - uses an extra set of Mission Cards, so there is some compatibility issues when playing with the 1st edition and 8 or more players.
Edit: Now that I look at the post again, this is in the "Hostile Intent" forum. All three modules included in Hostile Intent should be compatible, per the quoted information above.
The Trapper Module is included in the The Resistance: Hidden Agenda expansion.
Both expansions are included in the $20 pledge in the current Kickstarter.
If you are not familiar with the 2nd edition of the game, here is further information from Travis that I received after requesting clarification for the quote above.
Trapper uses an extra team token - in 1st edition that was a card instead of a token to indicate who was selected for the team before voting. So you could use the extra token in addition to the 5 team cards on last two missions when playing with 8 or more players (the 5 player missions). Its not perfect, but it would work.
Trapper also uses an extra set of Mission cards (Success/Fail) - those cards are different graphics between 1st & 2nd Editions, and I think different rounded corners, etc. I don't see a way very observant players to get around knowing which player was using the newer edition of the Mission cards. Therefore I don't think that Trapper would be compatible with older editions on the 5 player missions (8 or more players).