Did you know Via Rail has a fleet of British Rail Gauge train cars?
They obtained them from a failed sleeper service through the Chunnel in the 90s. I rode with them on the Montréal to Halifax rail service called The Ocean. Part of a big rail journey I took this summer across eastern Canada and Europe.
SJ has had rolling stock in continental gauges for such services. The Stockholm-Berlin sleeper train ran on SJ-branded ex-Deutsche Bahn wagons (which are now RDC-branded, now that the Swedish subsidy has ended).