When checking the distance of a path in Google Earth, it's total length is 2223 km. Bringing the KMZ into ArcMap, the distance I get from Calculate Geometry is 3303km. See attached pics.
What could account for the 50% difference? Within ArcMap, the data frame is set to Web Mercator 1984 (auxiliary sphere), as is the coordinate system of the shapefile I saved from the KMZ.