Paul often quoted scripture as a "spiritual application" and not in its wooden literal meaning. I good example is Romans 10:13
Rom 10:13 (AKJV/PCE)
(10:13) For whosoever shall call upon the name of the Lord shall be saved.
Note that Paul leaves out the "and it shall come to pass" (as well as mount Zion and Jerusalem), as he is NOT taking it in the context of Joel.
The verse quoted there is about being delivered through the great tribulation. Peter also quotes it in original context with much more of Joel.
Acts 2:14-21 (AKJV/PCE)
(2:14) ¶ But Peter, standing up with the eleven, lifted up his voice, and said unto them, Ye men of Judaea, and all [ye] that dwell at Jerusalem, be this known unto you, and hearken to my words: (2:15) For these are not drunken, as ye suppose, seeing it is [but] the third hour of the day. (2:16) But this is that which was spoken by the prophet Joel; (2:17) And it shall come to pass in the last days, saith God, I will pour out of my Spirit upon all flesh: and your sons and your daughters shall prophesy, and your young men shall see visions, and your old men shall dream dreams: (2:18) And on my servants and on my handmaidens I will pour out in those days of my Spirit; and they shall prophesy: (2:19) And I will shew wonders in heaven above, and signs in the earth beneath; blood, and fire, and vapour of smoke: (2:20) The sun shall be turned into darkness, and the moon into blood, before that great and notable day of the Lord come: (2:21) And it shall come to pass, [that] whosoever shall call on the name of the Lord shall be saved.
Original passage:
Joel 2:28-32 (AKJV/PCE)
(2:28) ¶ And it shall come to pass afterward, [that] I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions: (2:29) And also upon the servants and upon the handmaids in those days will I pour out my spirit. (2:30) And I will shew wonders in the heavens and in the earth, blood, and fire, and pillars of smoke. (2:31) The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of the LORD come. (2:32) And it shall come to pass, [that] whosoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD hath said, and in the remnant whom the LORD shall call.
Deliverance for the remnant when the LORD's judgment on the world comes.