As for performing Asr after Maghrib (1), this has never been permitted for anyone without an excuse, just as performing Maghrib before sunset has never been permitted.
They said:
Prayer must be performed within its appointed time under all circumstances, even if every other obligatory requirement must be omitted in order to observe that time. Thus, if a person can pray within the appointed time only by performing dry ablution, without recitation, without fully completing the bowing and prostration, while facing away from the qiblah, unclothed, or in whatever manner is possible, he must do so. He may not pray after the appointed time in order to perform all the actions in full. This is established by the Quran and Sunnah, and most of it is a matter of consensus.
It is therefore known that observing the appointed time takes precedence over every other obligation. Accordingly, if someone deliberately prays within the appointed time without recitation, unclothed, or under similar circumstances, and is then instructed to pray after the appointed time with recitation and proper covering, the act he is instructed to perform is inferior to the one he has already performed. Hence, if only one of these two options is possible, he must pray within the appointed time without recitation or proper covering; he must not delay the prayer and then perform it after its time with recitation and proper covering.
It is therefore clear that such forfeiture (2) is impermissible so long as it remains possible to avert it. As for one who has an excuse, Allah Most High has appointed his time for prayer as whenever he becomes able to perform it. Thus, whoever forgets a prayer or one of its obligatory elements must perform it whenever he remembers it (3), and that is its appointed time in his case.
If it is objected that his prayer would have been more complete had he performed it within the appointed time, the answer is: Yes, but that prayer was not obligatory for him, because sleep or forgetfulness rendered him unable to perform it. He was required to pray only once he awoke and remembered, just as we say regarding a menstruating woman when she becomes pure