Continuity Errors

Just watched A New Hope on TV and noticed what I think is a new continiuity error.

In the Droid sale scene, when the red R2 unit (R4-D5 I think) rolls of and then blows it's motivator luke calls out to Uncle Owen "What about the blue one?" The shot shifts back to R2 D2 and you can see the red R2 unit still next to him. Then it shifts back to Luke and the smoking R2 unit has shifted back.

This was in the Special Edition as screen on Sky Premier. Not sure if this has always been there or is only in the SE's that the mistake appears.

It's not only in the special edition it appears.
And it's not R4-D5, it's R5-D4

That mistake is in the original too.

Ok, so maybe it was just the first time I spotted it.

Funny that Luke calls it an R2 unit and not an R5 unit as well..... Anouther error....

Not TECHNICALLY a continuity error as it hadn't been called an R5 unit at any point... in fact, it was never called anything other than an R2 unit. So the R5 designation would be the error...

True. What was it called in the novel?

I think you can get different versions of the novelisation but in the version I have, Luke just called the red one a cultivator unit and never actually names it specifically.

The scene was devised differently originally I think. That's why there's this continuity error. I think Luke wanted to pick the blue one first, but Owen felt it was too beat up so he picked the nicer looking one. They probably didn't make a proper shot of R2 for this alternative cut.

Well there is that. The toy however was labelled R5D4. Anyway as to the what was on screen maybe they had more than one R5 unit and having seen one blow wasn't gonna risk another. As for names maybe Luke just aint that bright when it comes to Droid names or classifications and refers to them under a single banner label...