Withnail and I Facts and Trivia

Money
The film cost £1.1 million to make.  Bruce Robinson received £1 for the screenplay and £80,000 to direct it. Robinson reinvested £30,000 to shoot scenes (such as the journeys to and from Penrith) that HandMade Films wouldn’t fund.

Books
Regarded by some as the funniest book ever written, A Rebours is one of the books that Marwood puts in his suitcase at the end of the film. The other is David Copperfield.

Drunk Acting
Finally convinced that he needed to get drunk at least once to have the proper insight into the character, real-life teetotal Grant "filled a tumbler with vodka and topped it off with a bit of Pepsi", then swilled the whole thing down.

He was teased the next day by co-star Paul McGann and director Bruce Robinson, who assured him that he would never be so funny on film again.  In the scene where Withnail downs a bottle of lighter fluid, the can (which in rehearsals had been full of water) was full of vinegar. Director Bruce Robinson used vinegar on the take to get a better facial reaction from Grant.

Laughing
In the tearoom scene, Richard E Grant breaks out laughing. This wasn't scripted, but every time he spoke, he could hear the snorting of the dogs belonging to the old ladies at the table behind. After too many re-takes, the director gave up and kept the laughter in.

Camberwell Carrot
“The only spliff to utilise 12 skins” was actually made with herbal cigarettes.

I
Although credited on screen only as "I", Paul McGann's character is named as "Marwood" in the script.

It is widely believed that the characters first name is Peter. When "Withnail and I" go for drinks at Uncle Monty's, Withnail refers to Marwood (McGann) as "Peter" with the line: "Peter's had an audition for Rep..."

Motorway
During the motorway scenes, in the interior shots of the car, Paul McGann is seen to be driving, but in some exterior shots, the driver is actually director Bruce Robinson. The reason for this is that Paul McGann had only just passed his driving test when the film was made, and so was a bit wobbly on the motorway. Also, as he pulls away in London to set off for the Lake District, he stalls the car. This was unintentional, and was included anyway.

Monty Photograph
The photograph of Richard Griffiths in Uncle Monty's cottage is from The World Cup: A Captain's Tale in which he played a football manager and referee.