The first accident we've heard of that involved a MINI E resulted in a dent in the rear hatch and not much else. The fender bender – which took place at low speeds and was apparently the fault of a large white van behind the all-electric MINI in stop-and-go traffic – wasn't related to anything about the car's powertrain.
We know about the accident to MINI E #438 thanks to the My MINI E blog, part of a true blossoming MINI E blog network (see here, here and here) that describe the joys of driving the converted cars (and quick charging) in a way that BMW must be glad to see. As long as those rear-seat batteries survive any upcoming crashed without issue, then we expect the positive reviews to keep coming. Thanks to Yanquetino for the tip!