Unfortunately, Speed Review mode isn't available on courses testing on or prompting with images. At this time, this mode is only available on courses testing on and prompting with text.
If you keep receiving an error when launching Speed Review, this might be why. In that case, we advise clicking on the button with three dots (circled in red below) on the course's card on the homepage and selecting a different mode from the ones available.
If you're the creator of the course and want to use Speed Review, you can create new levels with the supported testing types and directions (i.e. text to text) to enable the mode.
If you believe you're experiencing a different issue, please get in touch with us.