Shooting into mirrors

Is there any particular angle that would affect the focusing and metering system of a camera and lens when shooting into mirrors, especially at an angle? This shot is slightly off a flat plane, but appears to be focused correctly. Just wondering if there is a limit shooting into mirrored glass at angles. I didn’t have a chance to experiment but it would be a fun exercise.

This shot was also posted over in People sharing.

EXIF: Av 3.5 * Tv 1/100 * ISO 1600 * AWB * Focal 35mm * No PP * No flash

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Remember that light is reflected from the subject to the mirror to your lens, so effectively you are doubling the focus distance.

But as you can see, the camera can read the image and focus just fine. It would only be a problem in low light or low contrast, both of which elements are essential for AF to function.