Before the Spotted Owl bus - which interior arrangements do not conform to the depicted exterior, including a rear window (with a shade) and a shelf with a microwave and courtesy paper cups perched on it - leaves on its journey, its number on the panel above the windshield is 7595, but when the bus rolls out into the street, the number over the door is 8544.
Just after George & Evan talk about him taking the handcuffs off the boy, a forward shot through a 3-way card game shows the bus number over the windshield as 7595. This is completely impossible, that having been the number when they rolled out of Los Angeles (though an exterior shot showed #8544) which broke down on some weathered 2-lane road they inexplicably got onto, then having to continue on a replacement bus which they kept all the way to Washington - that was #4560 on its outside.
This bus set a cinematic world's record before it even hit the highway - from the moment its front wheels touch the street to when it makes the entrance ramp to I-10 East, despite it threading its way through Los Angeles surface streets, for 8 minutes 54 seconds the bus never runs into a stop sign or red light, or makes even 1 turn, along the way..
While driving from South Los Angeles to Washington DC, the bus takes the Pasadena Freeway north from downtown LA. This freeway ends in Pasadena and is not the way one would travel across the country. Furthermore, a bus of this size would not be permitted on this freeway.
By evening on the second day of driving, the bus had gone from Los Angeles, CA to Memphis, TN (almost 1,800 miles). Despite driving through the night, by evening on the third day they had only traveled as far as Knoxville, TN (almost 400 miles).
When Jeremiah is in the hospital, George tells the others that the "Spotted Owl will be in front of the Lincoln Memorial." There is no way he could predict such a prime parking spot would be available for a bus due to the shear number of buses and other vehicles that would be coming into D.C. for the march.