When viewing EU airports in metric mode FlightWatch suffered from slight rounding error. The root of the problem was that when NOAA was fetching data for those stations, they converted the presented measurements into US standard units. As FlightWatch only had the NOAA data stream to work with, it was forced to convert them back into metric. Both of these conversions involved some rounding, so you would get odd results. An example of this is demonstrated by the metar below.
EHWO 121755Z AUTO 22009KT 2700 -RA OVC002 09/09 Q1009 AMB
The visibility and altimeter presented were 2700 meters and 1009 mb, but FlightWatch reported 2003.7, and 1008.93. FlightWatch 1.4.1 directly parses out metric visibility and millibars from the raw text, and if you’re viewing in metric mode suffers from no conversions.