- He may/might have gone (= It is possible that he went/has gone // Perhaps he went/has gone. He said/thought that she might have missed the plane. He came home alone. You shouldn’t have left him do that; he might have got lost, (But he didn’t get lost). You shouldn’t have drunk the wine: it may/might have been drugged. Perhaps we should have taken the other road. It might have been quicker; It’s a good thing you didn’t lend him the money. You might never have got it back. If we had taken the other road we might have arrived earlier.
[El giro integrado por ‘»may/might + infinitivo de perfecto«‘ se emplea para formular especulaciones acerca de acciones pasadas. might es obligatorio cuando el verbo principal está en pasado; might, no may, es la forma que se debe usar cuando no existe la incertidumbre ya: en la frase «You shouldn’t have drunk the wine: it may / might have been drugged» la alternativa con «may» («It may have been drugged») indica que todavía no sabemos con certeza si el vino estaba mezclado con drogas o no. «it might have been drugged» podría significar lo mismo, pero también podría significar que sabemos que el vino no estaba mezclado con drogas. might, no may, es también la forma que se debe usar cuando el asunto, lo enunciado como posible, no ha sido nunca sometido a prueba: «Perhaps we should have taken the other road. It might have been quicker»; oraciones de esta clase son muy similares al tercer tipo de oración condicional: «If we had taken the other road we might have arrived earlier.»]
2. If he sees you he will stop, (cierto) / If he sees you he may stop, (posible); If you poured hot water into it, it might crack; If you had left it there someone might have stolen it.
[may/might pueden sustituir en oraciones condicionales a will/would para indicar un resultado posible en lugar de un resultado cierto.]
A Practical English Grammar (A.J. Thomson & A.V. Martinet) 