Rose: The mistakes are mostly because the pronunciation of the two choices are the same.

Regarding just pronunciation:

You're = your
There = They're = Their

رضا: Yes, I realize that part. I think a lot of it is lack of written use in every day life. Most folks don't normally write or type very much except at sites like this. Maybe showing them the difference will help them to learn the difference. Just a thought.

رضا: There, Their & They're are not all pronouced the same!

There & Their are the same BUT They're is different

Lamby: Really? I have also always thought they're all pronounced the same way.

http://dictionary.reference.com/search?q=they%27re
http://dictionary.reference.com/search?q=their
http://dictionary.reference.com/search?q=there

Pedro Martínez: Hmmm I pronounce their & there as the link you put suggests, but I pronouce they're as....theyrrr
Maybe it's my accent?

Lamby: They're all pronounced the same, so I'd go with the accent theory. :)

rain, rein, reign
to, too, two, 2
for, four, fore, 4
lead and lead are pronounced differently!
lead, led
feat, feet, fete
read and read are pronounced differently!
read, red
read, reed

I'm surprised you guys didn't have the peeve with "our" and "are" as I see them mixed up all the time.
And why is it in English some words have acceptable alternate spellings and others only have one accepted spelling?
Honour or honor are OK, but don't you dare spell congratulations with a "D"

Walter Montego: Honour is UK/Canadian spelling - Honor is American

neighbor US / Neighbour UK/Canada (Common Wealth is likely the best way to say it)
flavor
harbor
color
etc

all the '-our' endings are Common Wealth

Same as some z words.. realize/realise etc US/Common Wealth

Rose: as well as 'analyse' and 'analyze'

at the university we were allowed to write our work either in american english or in british english ... but not in a mixture of both .. so if we started with 'analyze' we had to continue with 'color' as well ... the professors were quite strict on that

Hrqls: I guess that makes sense!

Rose: true .. but it also makes it a lot tougher ;)

especially since we learn british english in high school but learn american english from television :)

i love consistence though (is that the term?) .. brings structure in everything you do .. especially important while programming :)

Hrqls: It made it a little difficult for me when I was learning basic html. I would make a page with the colour tag and it never worked. Once I realized it was all 'set' in American English then I had no problem

Rose: lol true :)

glad they dont use american english in programming languages like basic as well otherwise it would be
'if ... than ... end if'

(just kidding! ;))

Rose: And about Congratulations, my assumption is:

The word Congratulations, according to dictionaries is pronounced /kengratsuleisnz/, with a CH sound, but people read it with a J (as in jam) sound which can occure just if a D sound and a Y sound come together, like in soldier which has originally been soldYer. So people think there must hav ebeen a D in congratulations too!

Rose: I agree with you..all that you have listed irritiates me too!