Harold leaves on his Pilmgramage from Kingsbridge in S Devon, He is next seen by the garage in Malborough ( South rather than North of Kingsbtidge). Good job someone gave him a compass or he would never have got out of Devon.
Maureen's first phone call is on brown phone in hallway; Second phone call it has changed to a business phone, then close up on handset is brown, then long shot is back to brown phone.
When Harold rings Maureen the first time, he puts the milk on top of the phone and doesn't retrieve it; yet a moment later it is back in his hand (outside the phone booth).
When Harold is having coffee with his wife he mentions not having any razors. But earlier in the movie he bought a whole bag of them. So this seems incorrect.