When Janet is driving Mike in the convertible and meets the lorry, Mike covers her head as well as his in the closeup shot. However in the long shot, they are each individually covering their own heads.
When Janet (Doris Day) crashes in to a lorry (truck) the driver has a sign stating "No Riders". While this is seen in the US, the signage is not commonly displayed in the UK where the movie is set.
When Janet is driving Mike in the convertible and meets the lorry, she is driving in the right lane and thus in the wrong. However in the close up shot of the two of them in the car, the car following them is also driving in the right lane.
At about the 1 hour 4 minute mark Janet is speaking about calling Mike but Doris Day's lips aren't moving.
The party band is heard playing rock and roll guitar instrumentals, but the band has no guitar player.