The last scenes set in London were actually filmed in Sheffield. The scene in "Kebabish" was filmed at Kebabish on the Wicker, in Sheffield. The other scenes were filmed on the Moor (a shopping area being renovated) and Campo Lane. Also, there are some shots where "For Sale" signs are visible and clearly show that they refer to Sheffield.
The market location where the trip to Pakistan was shot, is actually a city in India called Hyderabad. The license plates of the vehicles give this out.
The word Mashallah that the gang keeps using to each other literally means "It is God's will" but when used in everyday speech to a friend it generally means "good for you" or "well done."
Omar is walking through the park and meets his brother Ahmed playing football in the rain. Ahmed's umbrella goes from small to big for a close-up, then back to small again.
When Barry is driving the group to the airport in his Citroen Xantia, he pulls over in a huff and swallows the key to stop them going. However, the key he produces and swallows is a Ford key, not a Citroen key.
Additionally, the car is fitted as standard with a keypad immobiliser, requiring a security number to start - so Omar's attempt to hotwire the car would not have succeeded in real life.