Originally, Martin showed Frasier a picture of a Class C Winnebago that he bought. On this road trip, it's a Class A.
Obviously 31 December 1999 to January 1 2000 does not welcome in a new millennium, merely a new year.
There is no snow on the ground in any of the exterior shots, despite the fact that this episode takes place on New Year's Eve and the exteriors are all set in Idaho and eastern Oregon.
There's no 'e' in 'road warrior'.
When Niles called from the payphone, he said he was in Baker City, Oregon. Martin said that was 3 hours away (implied to the west). At the same location as Niles, Clifford said they were 150 miles back from the Little Red Cabin. That would place the Little Red Cabin around Boise, Idaho. Martin and Frasier meet Niles (presumably around Boise) and imply they have an hour to get to the Pacific Time Zone. It would take about an hour to drive from Boise to the Oregon border. However, when 1-84 heading west crosses from Idaho to Oregon at the Snake River, it remains the Pacific time zone until Baker County, Oregon. It is possible to drive from around Boise to the southern border of Baker County, Oregon (the beginning of Pacific Time Zone) in an hour, which would lead the only mistake being the line "We rolled back into Idaho". They would have rolled back into Malheur County, Oregon, not Idaho.