I see. It seems you are right. So it seems if I dictate something and don't send it to anyone - because I decide not to send it. And then I set my phone on fire and burn it to a crisp, my message is out there and can be retrieved? Very interesting.
Ahh, the old Android SMS Voice to Text Google Translation Covert Message Interception after the phone's been burned to a crisp trick, huh?!:icon_eek:
That's the second time I've fallen for that this month. 
I'll have to tell 99 about this!
But seriously, I wouldn't go so far as to say someone could retrieve it. It's an instant return message and in all likelihood the message isn't cached, meaning once it's sent by the Google servers, it's deleted. In other words, there's really no benefit for Google to devote any storage capacity for these instant translation messages since they can't be "retrieved" in the traditional sense of the word, by an FTP request or a URL location, etc. They're probably only held in RAM on the Google servers long enough to assure they've been delivered to the phone from which the request came.
In order for them to be retrieved by an unauthorized party the person attempting to retrieve them would first have to know long before then that the message was going to be transmitted, then at that precise moment know they've been sent, intercept during the return transmission, and spoof the Google servers to convince them that the spoofing phone is the intended recipient. This is a moment in time that would take a tremendous amount of pre-planning to pull off, and for what?
If this were being used perhaps to carry information of national security, and it were known well in advance that this information was going to be conveyed, MAYBE a rogue nation MIGHT be able to intercept. Otherwise, I would say anyone who is THAT fearful of their data being intercepted in this method has greater issues than whether Google has access to and is storing such information, and probably shouldn't be using standard SMS or POP3 protocols, etc., to do so.