The amount of times the same vehicles were used, even after being involved in accidents. Example: when the bikers are trying to kill themselves, one rides through the side of a furniture van. Later on, the riders go past traffic and the same van is there undamaged.
When Tom drives his bike through the wall, the wall breaks. However in the next shot you can see the wall behind him completely unbroken
When the gang buries Tom, they didn't dig the hole for him sitting on his motorcycle deep enough: you can clearly see that his head is above ground level. Once the fresh grave mound would have been gone, his head would have have been sticking out of his grave.
As the camera pans across the morgue, a sink is seen without any plumbing hooked up to it.
One of the chase scenes where the bikes are followed around a road, pre 1959 road markings are seen. While it is possible older style UK road markings were still in existence in 1972, they would not have been on main roads. This probably confirms that the road used was a test track for motor vehicles rather than national highways.
When Jane Pettibone is pretending to be hung from a tree by a rope a caribiner clip is visible behind the rope she is supposedly hung by as she moves around.
Even if Tom was indestructible after coming back from the dead, that wouldn't make his motorcycle indestructible or weaken the wall so he could crash through it.