Since they failed so completely at explaining mirrors; reflections aren't flipped, they show exactly what they "see".
The right side of your face is reflected on the right, your left hand is reflected on the left. It's the brain that can't work out that a reflection isn't another person facing you.
Text isn't flipped either. The word "boss" was the same way round, the B was on the right, the Ss were on the left, exactly how they were when the card was held up.
Sandi messing with the paper was just weird.