The caveat has been filed to ensure that the High Court does not pass any order on Mistry's plea without hearing Tata Sons.
A team of lawyers including Abhishek Singhvi and Harish Salve are advising the Tatas. Singhvi left for Mumbai on Tuesday evening.
Singhvi told Times Now that almost the entire board of Tata Sons - seven out of nine - had lost confidence in Mistry. He said the loss of confidence was palpable.
Ratan Tata, the interim chairman, was committed to brand Tata and whatever he did was for the group's improvement, Singhvi said.
Mistry was removed as Chairman of the Tata Sons on Monday and replaced by Ratan Tata who would act as interim chairman till a replacement for Mistry is found.