The license plate on Harry's truck changes between scenes. For example when he leaves the diner after the fight it is SLP-672 and when he arrives in Glasgow it's OLO-482.
After crossing the river at 1:14 with the left front tire removed the truck climbs the bank of the river with all 4 front tires. -- It's the whole left frontmost wheel that's removed, not just the tyre. And after the wheel is removed it does not reappear: after the lorry crosses the riverbed, that left front part of it is not seen again until it reaches the loading pier, and then the left frontmost wheel is clearly missing.
When the lorry pulls up by the ship, Lynn is sitting right next to the left-hand window, thus with a seat between her and Harry. In the next shot she's suddenly in the middle of the cab holding Harry.
When Harry and Casey first leave the Liverpool depot, Casey goes first in a 1949(ish) Leyland Octopus, Harry second in a 1955(ish) Leyland Octopus. later in the same journey, both vehicles are the later model.
Harry's first run in the UK is from Liverpool to Glasgow, Scotland. A sign is shown stating that he is driving on the A59 road and that it is 213 miles to Glasgow. However the A59 ends in York, North Yorkshire in England - way to the south of Glasgow. The road distance is approximately correct. -- No error here: the sign confirms the road number at that point; it does not imply that it applies all the way to Glasgow.
When Easy abandons his car after turning back at the roadblock it has peculiar dark covers over the unlit headlamps - perhaps to prevent reflections from the film-crew's lighting. These covers were not in place when he left the Glasgow depot shortly before.
When the doomed lorry is driven up to the cliff-edge, the face of Casey the driver can be seen clearly as he leans out of the door - except that it's not him.
Connie says that the real father of her child is 'Al' - but there's no such character in the film. Sounds like a part that was written out at some point.
No attempt is made to explain why Lynn has an American accent but her brother Frank has a British accent. They are roughly the same age and shown to be close, suggesting the characters grew up together. Both are shown getting upset, which for most people would cause a learned accent to slip, if Lynn was meant to have lost her accent for work. -- This is wrong: Lynn does not have an American accent - it's pretty-standard RP English.
When Joe Easy drives off with Frank about fifty minutes into the film, a reflection of a studio light on scaffolding is visible in the right rear window of Easy's car.
Embarking on a cross-country trip of15+ miles in the Scottish highlands in a laden 10-ton eight-wheeler on completely unknown tracks with no guidance other than an Esso 5 miles-to-the-inch roadmap is clearly crackers - whether you're a desperado or not.