Visible crew/equipment: In the desert, Helmet asks the guys "combing" the desert if they've found anything. The camera crew is reflected in the helmet of the guy that says "we ain't found shit."
Revealing mistake: When Vespa starts shooting at the guards on the platform, the one on the end flips over when shot, and you can see him bend over after he's shot to prepare himself for the stunt.
Continuity mistake: As the shaving guard falls, he gets shaving cream on Lonestar's right jacket arm. In the next shot Lonestar reaches down to grab the badge and that same arm comes into view and it is completely clean. There isn't enough time between shots for him to have wiped it off.
Continuity mistake: When Dark Helmet takes the ring from Lonestar, he throws down into a grate. Later, when Megamaid explodes and Lonestar and company cheer, for a brief second, you can see the ring back on his finger.
Answer: Its a reference to how the stars streak around the ships in "Star Wars". "Ludicrous speed" had to have a ludicrous color. It is also referencing 2001: A Space Odyssey, where this "tartan" effect occurs when Dave is in the pod towards the end of the film.
Grumpy Scot
Those answers are quite correct and possible, but how about this: Warp and weft are the two directions of yarn in weaving (of plaids and other things). It might be a very meta joke since plaid is at much higher level than warp. On the other hand, it's Mel Brooks. On the gripping hand, he was born in Brooklyn in the mid 20's and might have been exposed to the basics and vocabulary of the tailor at a young age.
Btw, it's also a clear reference to the sentence from Star Trek "They've gone to warp."