Majlis Ulema of South Africa has published a book called "Errors of Yusuf Ali" and they have listed 16 major mistakes of his in translation and commentary.
Under Ayat No.275 Surah Baqrah he says:
"When we come to the defination of usury there is room for difference of opinion...The defination I would acceot would be: undue profit made, not in the way of legitimate trade, out of loans of gold and silver...My defination would include profiteering of all kinds, but exclude economic credit, the creature of modern banking and finance."
So he says riba offered by modering day banking is allowed, or is not even riba.
According to him Risalat is not a requisite of Iman. Read under Ayat 62 of Surah Baqrah where he says:
"The point of the verse is that Islam doesn't teach an exclusive doctrine and is not meant exclusively for one people."
Also his denail of Hoor in Jannat and he has come up with a new defination of the word "Hoor".
According to him Jannat is just symbolic and purely spiritual and not material or physical. This was the belief also held by philosophers like ibn Sina, Farabi etc.
Also when talking about Hazrat Isa , he says:
"The end of the life of Jesus on earth is as much involved in mystery as his birth..."
Mystery? There is no mystery, we as Muslims believe he was raised up alive with his body. This is how he creates doubts in the minds of Muslims.
Then he says:
"One school holds that Jesus did not die the usual human death...another holds that he did die but not when he was supposed to be crucified, and this his being "raised up" unto God means that instead of being disgraced as a malefactor, as the Jews intended, he was on the contrary honored by God as his Apostle."
Here by the other school he is referring to Qadyanis.
And under Ayat No 33, Surah Maryam, he says:
"Christ was not crucified. But those who believe that he never died should ponder over this verse."
So he is again doing the Qadyani talk and propagating that Hazrat Isa has died a natural death.
These are only few glimpses. Those who can buy the book I have mentioned above, should get it. I will try to scan the whole book and make it available online.