I always watch this scene fairly intently and it annoys me every time. 

Immediately after McQueen rolled out of the trailer, there were a lot of cars on the highway, and this despite the fact that a few seconds ago it was empty, there was no one on it except Mack and four street racers. It’s just somehow really strange: when Mack was driving, falling asleep, there was no one on the track except him and the street racers, the track was empty, and when McQueen was already chasing Mack, there were already a bunch of cars on the track, somehow they all appeared very unexpectedly, as if they had teleported. And it was also strange that they all appeared immediately after McQueen rolled out of the trailer, not earlier and not later.

We SEE Lightning start down the road, maybe only 20-25 seconds behind Mack. He didn’t know he was 20-25 seconds behind, sure. But even then, he’d have seen him. McQueen was only asleep on the road for maybe 2 minutes max (being generous because he actually wakes up in like 15 seconds), but Mack at most would've only been a couple miles ahead if McQueen kept going. He was stupid af in the first movie. We only see like 6 trucks pass Lightning whilst he’s asleep and subsequently dazed. Lightning then gives chase and passes like 5 trucks looking for Mack. I don’t actually think a single truck passes him as he sleeps. I know he can’t know what passes him while he sleeps, but it just doesn’t sit right with me that we’re expected to believe he can’t find Mack when really, Mack wasn’t especially far ahead and only a few trucks separated them. Lightning is passing traffic within a second or two of getting moving. He’s accelerated FAST. The traffic Lightning gives chase to isn’t at all consistent with the traffic that passes him. A bunch of trucks just kind of appear out of nowhere. I know it’s a kid film, it doesn’t ruin the film by any stretch. But as an adult, I can’t unsee it.

In this scene, a bunch of trucks just kind of appear out of nowhere and is looking for Mack obviously to set up the scenario