2 of 6 added 7 characters in body

exception in the past tense clauses sequence rule?

As all of us know as a general grammatical rule,the verb tense in second clause which comes after a simple past tense clause must be in one of the past tenses. For example:
She knew she had made the right choice.
I touched the baby's head who was crying.
But I wondered when I saw this sentence.
I heard a little boy waving his hands above the water.
Shouldn't it be:
I heard a little boy was waving his hands above the water?
Are there any exceptions to this grammar rule? If yes,what are those specific verbs ?