When Albert (Wilfred Bramble) is preparing to go out with Harold to the stag night, he is clean shaven but when he arrives at the the show, a few hours later he has several days growth of beard.
Baby Albert is wearing a blue babygrow when he's carried across the yard by Harold. He's not wearing it when Harold enters the house with him, and he hasn't got it on when he's discovered in the barn by Albert and Harold in the first place.
During Steptoe and Son's night out watching the stripper, Albert's hair changes from ruffled to neatly combed and back to ruffled within a few frames.
The morning after the night out seeing the stripper, after Albert has slept in the stable, as he picks up the milk on the doorstep he has rough facial hair. When he takes the milk into the house he is clean shaven.
The events of this film are set around 1968-1969, but Harold is seen riding into the yard with Delilah - who hadn't been bought by the Steptoe's until 1970 when their previous horse Hercules died. He is who should have been at the reins.
Albert says hymn no. 389 is "Fight the good fight". This is incorrect.
The horse faeces that Harold picks up and puts in the bucket at the beginning of the film are clearly little potatoes painted brown.
At the end of the film, when Harold and Albert get beeped at and overtaken by Prince Philip's Rolls-Royce, they are going down Great George Street, with Big Ben a short distance behind them. But in the next shot, with the Rolls-Royce still just in front of them as if only a few seconds have passed, they are suddenly on the Mall approaching Buckingham Palace, about a mile away.