To supplement the answer by @TheZ, the following explanations are also possible:

• The Bani Israel could have temporarily returned to Egypt after the drowning of Pharaoh. This has been claimed in some traditions recorded by the exegetes, and this is also one of the possible interpretations of another verse 2:61:

  اهبطوا مصرا فإن لكم ما سألتم

  Go into 'Egypt' and indeed, you will have what you have asked

  ^{— Quran 2:61}

• It is possible that it means only the treasures i.e. the movable items that the Bani Israel took with them when leaving Egypt. This is present in the Torah:

  Every woman is to ask her neighbor and any woman living in her house for articles of silver and gold and for clothing, which you will put on your sons and daughters. And so you will plunder the Egyptians.”

  ^{— Exodus 3:22}

  The Israelites did as Moses instructed and asked the Egyptians for articles of silver and gold and for clothing. The Lord had made the Egyptians favorably disposed toward the people, and they gave them what they asked for; so they plundered the Egyptians.

  ^{— Exodus 12:35-36}

• It is possible that "springs and gardens" means those which are present in Palestine \ Syria as this area was part of the Egyptian Kingdom or was its vassal, see here.

And there are also other possible interpretations.

To supplement the answer by @TheZ, the following explanations are also possible:

• The Bani Israel could have temporarily returned to Egypt after the drowning of Pharaoh, before continuing their journey towards Syria. This has been claimed in some traditions recorded by the exegetes, and this is also one of the possible interpretations of another verse 2:61:

  اهبطوا مصرا فإن لكم ما سألتم

  Go into 'Egypt' and indeed, you will have what you have asked

  ^{— Quran 2:61}

• It is possible that it means only the treasures i.e. the movable items that the Bani Israel took with them when leaving Egypt. This is present in the Torah:

  Every woman is to ask her neighbor and any woman living in her house for articles of silver and gold and for clothing, which you will put on your sons and daughters. And so you will plunder the Egyptians.”

  ^{— Exodus 3:22}

  The Israelites did as Moses instructed and asked the Egyptians for articles of silver and gold and for clothing. The Lord had made the Egyptians favorably disposed toward the people, and they gave them what they asked for; so they plundered the Egyptians.

  ^{— Exodus 12:35-36}

  And some exegetes have also linked this to the items mentioned Quranic verse:

  حملنا أوزارا من زينة القوم

  we were made to carry burdens from the ornaments of the people [of Pharaoh]

  ^{— Quran 20:87}

• It is possible that "springs and gardens" means those which are present in Palestine \ Syria as this area was part of the Egyptian Kingdom or was its vassal, see here.

• It is possible that the Egyptians lost their wealth and the Bani Israel gained (other) wealth and properties similar the Egyptians. It is not necessary that they gained control over the exact same properties which had previously been owned by the Egyptians.

And there are also other possible interpretations.