The Belgian royal palace is actually in Brussels. There is a hotel in Bruges that had been a Duke's palace in the 15th century.
The chocolate that Luc and Emma are presenting seems to be at least 4" high yet the box they bring it in seems to be no higher than 3" at the most.
In het beginning of het movie Emma says "de ballen" to Luke. Bruges is in Flanders Belgium this isn't a flemish expression but a Dutch one.
Earlier in the movie, Emma asks what the prize is for winning the chocolate Competition. The response was prestige and a plaque, but they receive a trophy at the end for winning.