Looking back at my logs, my shortest widebody flights in the US were:

• US 767-200 PHL-CLT (448 miles, 2007)
• UA 777-200 DEN-LAX (860 miles, 2009, upgraded to a Global First seat using 1P 500-mile upgrades)
• AA A300-600 JFK-MIA (1091 miles, 1996 and 2007)
• AA 777-200 DFW-MIA (1119 miles, 2000; the same aircraft I flew in on from KIX earlier that day)

DFW-MIA still gets widebody service (on an even larger 777-300ER!) but the others don't.

My shortest widebody flight ever was 120 miles, on a route that no longer exists at all: SNN-DUB on an EI 747-100 in 1990. Of course this was back when all the transatlantic flights to DUB had to fly into SNN, so a bit of a cheat.

Another memorable one outside the US was a 234-mile, less than 1-hour QR 777-200 flight from DXB to DOH in 2015, where I got a meal and four glasses of champagne in F...