If one misses some of the takbeers of the funeral prayer

He should join the prayer with the imam wherever he catches
up with it, because the Prophet (peace and blessings of Allaah be upon
him) said: “Whatever you catch up with pray, and whatever you miss, complete
it.” When the imam says the salaam, he should complete whatever he missed if
the bier is still there and has not been taken away. If he is afraid that it
will be taken away (before he finishes), then our fuqaha’ – may Allaah have
mercy on them – say that he has the choice of completing the prayer or of
following the imam, and saying the salaam with the imam. And Allaah knows
best.