What to ask when interviewing at an acquired startup?

If your interviewer was there pre-acquisition, ask them what they think changed as a result -- and then ignore their literal answer, which will almost certainly be carefully-guarded bullshit, and listen very very carefully to the tone.

Are they hedging ("not much has changed, honest, just a few little things")? Are they wildly excited ("omg things were on fire before and now we're so much more stable")? You're looking for red flags that suggest the old guard made bank and are already testing the strength of their golden handcuffs and biding their time until they can make a run for it. You don't want to be left holding the bag when that happens...