שמות יב:יא - וככה תאכלו אתו, מתניכם חגרים, נעליכם ברגליכם, ומקלכם בידכם, ואכלתם אתו בחפזון, פסח הוא לה' י
Shemot 12:11 - Thus shall you eat it, your waists with belts, your shoes on your feet, your cains in your hands, and you shall eat it in haste, it is a Pesach for Hashem.
It seems from here that we had to be ready to leave Mitzraim in a hurry. But elsewhere we see that we actually didn't leave the night of the 15th of Nisan, but rather during the day.
במדבר לג:ג - ויסעו מרעמסס בחדש הראשון, בחמשה עשר יום לחדש הראשון, ממחרת הפסח יצאו בני ישראל ביד רמה לעיני כל מצרים
Bamidbar 33:3 - And they traveled from Raamses in the 1st month, on the 15th day of the 1st month, the day after the Passover, Bnei Yisrael went out of Mitzraim with a high hand, in front of the eyes of all Mitzraim.
So on the one hand we are told that Am Yisrael left in Chipazon. The other hand, we didn't leave until the next day, in a triumphant fashion.
So what is the Chipazon then?
At the end of Parshat Shemot, Moshe complains that only bad has happened to Am Yisrael since he started his mission. Hashem's response is as follows:
שמות ו:א - ויאמר ה', עתה תראה, אשר אעשה לפרעה, כי ביד חזקה ישלחם, וביד חזקה, יגרשם מארצו
Shemot 6:1 - And Hashem said: Now you will see what I will do to Par'oh, for with a strong hand he will send them, and with a strong hand he will expell them from his land.
So here we have the Hashem replying to Moshe that the appointed time has come, and the direct intervention from Heaven will cause Par'oh to expell Am Yisrael from Mitzraim. Ponder that verse for a moment.
There is an argument in the first chapter of the Talmud Bavli Brachot as to whether or not the Chipazon is Am Yisrael's or Mitzraim's. Rashi brings, on the word Chipazon in Devarim, that the Chipazon is Mitzraim's. On a certain level, we celebrate/commemorate the fact that they couldn't get rid of us fast enough. This is not a negative occurance, but rather a positive promise from Hashem that was fulfilled in the unfolding of the Exodus.
We are at the end of the Final Galus, and we are told that this Chipazon will not exist. Is this a good thing or a bad thing?
The pasuk in Yeshayahu makes it sound like a positive development, "for Hashem will go before us". This could make one think that the Chipazon in Yetziat Mitzraim was Am Yisrael's, despite the opinion brought by Rashi. Nonetheless, just like there are two ways to think about the Chipazon in Yetziat Mitzraim, so too I cannot help but think that there is more than 1 side to the pasuk in Yeshayahu.