Just read the little History page on the main page, and all I have to say is:
The Pizza
Planet truck is during the Freeway scene in The Incredibles. It’s quick. VERY
quick.
You’re gonna have to get me a screen shot to believe it =P
Several of us have combed that scene frame by frame but are yet to come up with it. 
I’ll see if I can find one . . . not too good
with computers, see . . .
If you told
me the exact time it happens, I might be able to screencap it for you.
I guess it’s here : when the
Incredibles are back in town, they “land” on the freeway with a white and blue vehicle. Now, on the
shot of the impact, and some frames before it, you can see the P?zza Planet Truck going very quickly from the
left to the right, in the bottom of the screen.
Actually what you can see is the yellow roof and the
rocket, but again, very quickly : you’ll have to watch it frame by frame.
I would do a screencap myself
if I could, but all I can do is a photo of my TV screen 
Sorry, after a frame-by-frame
viewing, it’s not there.
And yet
I’m pretty sure it’s there. I’ve just tried to take a photo, but I can’t have something clean enough on my
TV. I’ll try something else ; it’s not over 
Hehe, you’d think somebody would’ve posted a
screencap of that truck on the internet by now! 
So, I finally decided that the photo was the
only way I could show where exactly I think the Truck is located.
First,
this image.
And in
this one, I circled in red what I believe is our
Truck.
So, what do you think ? I know the quality is low, but maybe you’ll be able to see it better on
your DVD, and you’ll make your own opinion.
Dang that is hard to see!! Maybe . . . .
Hmmm that could be it. That couldnt be it. Now that people can see where he is
looking someone might be able to get the screenshot.
Could this be it? Could Pixar Planet go down in the
history books for the first people to find the location of the Pizza Planet Truck?
I noticed that car too when going through that scene… but
I just couldn’t see it being the Pizza Planet truck. I wish we could some clarification from the big Pixar guys
on this, lol.
Anyone else feel like we’re
trying to prove the existance of big foot or nessie? LOL
Another thing that would help is a clear
screenshot of the truck in a different movie for comparison. It should be the same model so perhaps we could
compare unique impressions ala fingerprinting [/CSI geekiness] 
Here’s the Pizza Planet Truck from Cars. (it’s on the very
left)
[img]http://img.photobucket.com/albums/v441/aggiechan/pizzaplanettruck_cars.jpg[/img:7a1f
e9c896]
Yes, we need to
make Brad Bird talking 
If we press hard enough, he’s gonna admit it’s the Truck (at least, hopefully).
Ahaha that’s so cute XD
Right, the one in [i]The
Incredibles[/i] looks mostly white to me, whereas the Pizza Planet delivery truck is yellow with a
white compartment at the back. Which end of the truck is the front?!
All the traffic goes the same way on the road, so the front is on the left of that
image.
I’d also note the blue car behind it - see how it also
appears that car has a rocket on top? It’s an optical illusion caused by seeing the roof and seeing through the
windows beneath it. I think the same may be the case on the other vehicle we are scrutizing because when you
take that into account I no longer see a rocket.
In the second one yeah, the first one it definitely looks like there’s a shape there, which is why I
thought it was a cab - the problem with this scene is that they reused a lot of the vehicles so when it switches
to the front shot you see a lot of blue and yellow cars behind the trailer that weren’t the ones they passed in
the side shot but are, in the case of the blue car, the same model.