Much of Bob's lines do not seem to have the inverted effect on them, and actor Frank Silva appears to be simulating the effect himself at times with his vowel accentuation (could possibly be due to the difficulty in speaking the lines both backwards and in a maniacal way when recording).
When Cooper enters the Black Lodge he is wearing his coat, but when the scene changes and is shown inside the Black Lodge he doesn't.
In the bank scene, when the teller is bringing Audrey a glass of water, a boom mic is clearly visible at the top of the screen for several seconds.