The conductor would have to have woken Ross up to check his ID or passport therefore he would be well aware he was crossing the Canadian border into Montreal.
When the rebellious employees lock Monica in the fridge, she spills marinara sauce on her self. She emerges moments later, but the sauce is nothing more than a large dried stain. She should have wet sauce dripping off of her chef's uniform.
Monica supposedly gets locked in the walk-in. No one who has worked in a kitchen for more than a day doesn't know there is a handle on the inside. There is also a light, so there is no reason at all for her to supposedly be locked inside unless it's her first day of chef training.
The train journey from Poghkeepsie to Montreal is almost 10 hours, very unconvincing that Ross napped for 10 hours.
When Ross wakes up in Montreal, the woman beside him says she lives in Nova Scotia, "a two-hour ferry ride" from Montreal. In fact, there is no ferry between Montreal and Nova Scotia; the nearest part of Nova Scotia is about 940 km (584 miles) from Montreal by road. (Manhattan is only about 587 km, or 365 miles, from Montreal.)
When Ross is asleep on the train, the conductor announces that the train will be arriving in Montreal, while he is talking to the woman beside him, you can clearly see a sign saying "Penn Station" through the train window.